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“FLACK-FLACK-FLACK”—AGAIN HE HEARD THE HORRID SOUND OF LEAD RIPPING THROUGH SPRUCE AND FABRIC NEAR HIM

THE  SPY  FLYERS

 

 

BY

CAPTAIN  W.  E.  JOHNS

 

AUTHOR OF

“THE CAMELS ARE COMING,” “FIGHTING PLANES

AND ACES”

 

ILLUSTRATED BY

HOWARD  LEIGH

 

 

 

 

 

LONDON

JOHN  HAMILTON  LTD

1933

The Spy Flyers

Rat-tat-tat-tat-tat. Rat-tat-tat-tat. Captain Rex Lovell, R.F.C., flung his joystick over and kicked the rudder-bar in a wild half-roll out of the devastating blast of lead that had scored the top of the fuselage of his Bristol Fighter not a foot from his head. He looked around anxiously at his observer, Tony Fraser, and breathed a swift gasp of relief. Tony was braced back against the side of the rear cockpit, eyes glinting along the barrels of his twin Lewis guns upon which he had just clamped a new drum of ammunition with the deft speed of long experience. Rex saw two tongues of orange flame leap from the muzzles, and then turned again to the work on hand, thankful that Tony had not been hit.

A red and green Fokker tore across his sights. Rat-tat-tat-tat-tat-tat—he thumbed his triggers viciously and plunged down in a wire-screaming dive in hot pursuit. He saw the pilot slump forward in his seat and he zoomed up again with the exhilarating feeling of exultation that follows a victory. Flack-flack-flack-flack—again he heard the horrid sound of lead ripping through spruce and fabric near him. Spang-g-g! Something smashed against the root of a centre-section strut near his face and he banked steeply. Tony’s guns were chattering incessantly behind him as the gunner pumped lead into the wheeling black-crossed machine.

“Phew,” gasped the pilot, “this is getting a bit hot.” All around him guns were stammering little staccato bursts. He snatched a swift glance behind and saw a silver-bellied Albatros plunging earthward in a cloud of black smoke streaked with tongues of orange flame. Tony’s shrill yell of victory was borne faintly to his ears above the noise of the engine.

“I wish he wouldn’t yell like that,” muttered Rex irritably. “He gets as crazy as a Red Indian when he’s fighting”—he swerved violently to avoid colliding with another Bristol and an Albatros which, locked together, were spinning wildly downwards in a last ghastly embrace. He caught sight of a large B painted on the nose of the Bristol. “Poor Jimmy’s out of it,” was his unspoken thought, and he whirled in a blaze of fury at a Hun that was charging at him head-on. “All right, come and get it,” he snarled. “Turn, you devil, or I’ll ram you.” His tracer was making a glittering line straight into the engine of the enemy plane, but the enemy pilot was shooting, too, as the quivering thud of bullets ripping through the Bristol testified.

At the last instant, only when collision seemed inevitable, the Fokker zoomed, and Rex flinched instinctively as its undercarriage wheels flashed past, a matter of inches from the leading edge of his top plane.

“This isn’t funny,” gritted Rex as he gasped out a mouthful of acrid cordite gas. Where were the others? He looked around anxiously and noted that, as usual, the dog-fight had lost height rapidly. The combat had started at 12,000 feet and they were now within 3,000 feet of the ground, immediately over no-man’s-land; the wind, blowing from the east, a rare event, was blowing the fight farther over his own side of the lines. Below him two planes were smoking on the ground and the two machines that had collided were piled up in a ghastly heap of debris on a communication trench. An Albatros, standing on its nose in the German front-line trench, was being frantically shelled by the British artillery.

Suddenly his eye fell on something that made him stiffen in his seat, whirl, thrust the stick forward and plunge downwards. It was the Hannoverana that had been the cause of the trouble. The two-seater had been used as a trap, a lure to bring down his Flight from a high patrol to the waiting guns of a Boche circus. The Hannoverana pilot, his work finished, was streaking for home, but he had left it too late. Rex was above him and used his height to advantage. He took the black-crossed machine in his sights and sent a stream of glittering tracer into its double tail. The enemy pilot looked up, and saw death staring at him in the spouting muzzles of Rex’s twin Vickers guns. He veered crazily in a fruitless effort to throw the gunner off his mark, but Rex, fighting mad, was under his tail now, in his “blind spot,” and nothing could shake him off.

“You’re my meat,” he muttered grimly as he closed in to deliver the final burst of fire that would send the other plunging earthward on the long drop to oblivion.

But the Boche knew that the end had come. His gunner was struggling to keep his feet in the swaying machine in order to get in an effective burst at the Bristol, but in vain. The German pilot, having no desire to pile his machine up in the wreckage below, took the only course possible to save his life. He cut off his engine and flung up his arm in a despairing gesture of surrender.

Rex smiled sourly. “Pack up, would you? All right, I suppose I’ve got to let you get away with it.” He jabbed viciously towards the British lines with his gloved hand. The German made a signal of understanding and turned his machine in the desired direction. The other machines had disappeared with the amazing suddenness that is a peculiarity of air combat, and Rex followed his victim down unmolested.

A few salvos of archie pursued them as they sailed into the comparative security of their own lines, the German machine still under the guns of the Bristol. Five minutes later the Bristol pilot’s aerodrome at Maranique loomed up ahead, and Rex signalled to the other to land, afterwards turning to grin broadly at Tony who was following the proceedings with intense interest.

The Boche needed no second invitation. He planed down quickly and landed, Rex close behind. Almost before the Bristol had stopped its run, Rex and Tony were out sprinting for the German machine. They were just in time, for the crew were feverishly working to release the device fitted to nearly all German war planes, which enabled a pilot who was compelled to land in enemy territory to set fire to his machine and thus prevent it falling into the hands of the other side.

Rex seized the German pilot by the collar and flung him clear of the machine. “No, you don’t,” he snarled grimly in the German language. The enemy pilot stared at him.

“You speak German?” he asked quickly.

Rex nodded. “All right, never mind the machine, we’ll take care of that. Come on.”

They turned towards the little crowd of officers and mechanics who were racing towards them, and in a babble of excited voices they entered the officers’ mess.

During the war it was customary for captured airmen to spend the evening as the guests of their captors, and Headquarters had a good reason for not opposing this curious and irregular procedure. In many cases the airmen, suffering from reaction after the combat and thawed by the comradeship around them, often let slip scraps of information which were of vital importance to the authorities. More information was probably gained in this way than from any other source, in spite of the fact that airmen were constantly warned to remain dumb if they were captured.

On the evening in question the officers of 297 Squadron entertained another guest besides the two prisoners. This was Major Trevor who had come over from Intelligence Headquarters, presumably because he wished to study and hear what the two prisoners had to say before they really awoke to their position. During the evening Rex and Tony acted as interpreters, and when the two captured airmen had finally departed for less pleasant quarters, the Major, who had been in earnest conversation with Major Lukers, the C.O., called them over to him.

A tall, handsome, middle-aged man with eyes of steely-grey, he looked every inch a soldier, and Rex approached him with respect.

“I saw your dog-fight from an observation post near the front line,” began Major Trevor smiling, shaking hands with each of them in turn. “A good show—a rattling good show. Major Lukers tells me that you are going to make names for yourselves.”

“Oh, I don’t know about that,” replied Rex modestly, acting as spokesman for both. “It’s all in the day’s work, you know.”

“By the way, how is it that you two speak German so well?” asked the Major in surprise.

“We were at Heidelberg together, sir,” replied Rex.

“Heidelberg?”

“Yes, sir, we were at school together before that. My guvnor is a director of the National Chemical Company and wanted me to join the firm when I left school. A lot of the chemical business is done with Germany, as you know, so I was sent to Heidelberg University to learn the language and study chemistry. I wanted Tony in the business with me, so we both went. We were there for nearly three years, and, as a matter of fact, we were only just home when war broke out. We joined the R.F.C. together. The Medical Board wouldn’t pass Tony as pilot, but let him go through as an observer, and at the Pool we wangled it to get up here in the same squadron. To-day is the first opportunity we have had for airing our German since we left Germany,” he concluded.

“Well, you seem to have remembered it all right,” smiled the Major, and then he became serious. “Come and sit down over here quietly for a moment, I want to speak to you privately—I have the C.O.’s permission.”

Major Lukers nodded and strolled away to join the other officers round the fire.

“Have you boys ever heard of ‘secret missions’?” began Major Trevor when they had settled themselves comfortably in a corner.

“You mean spy-dropping, and so on?” answered Rex quickly.

“Ssh—that’s not a nice way of putting it,” replied the Major, frowning, “but that is what it really amounts to, I suppose.”

Rex nodded. “I’ve heard something about these things that go on; queer rumours float about the tarmac, you know.”

“Well, there are other jobs besides spy-dropping, as you call it,” went on the Major. “There is a job waiting to be done now, a job demanding a good deal of nerve and ability.” The Major studied the end of his cigarette reflectively.

“You mean——”

“Exactly. After seeing your show to-day, I thought you might like to take it on. A successful issue would no doubt result in a decoration.”

Rex made a deprecating gesture. “I’m not concerned with that, sir,” he said simply. “Tell us about the job and let us get down to it.”

The Major edged his chair a little closer and dropped his voice to a whisper. “Have you done any night-flying?” he asked. “Good,” he went on, as Rex nodded in the affirmative. “You know the Lille-Le Cateau railway line?”

Again Rex nodded. “Perfectly,” he said.

“Very well,” continued the Major. “A mile from the village of Maricourt along the line, there is a tunnel. That tunnel is of vital importance to the enemy. They are using that line to bring up reserves and supplies, or they will be when the big spring show starts. If anything happened to that tunnel the line would be effectively blocked.”

“Why not bomb the line?” suggested Tony.

“Useless,” replied the Major shortly. “We have already done that. Direct hits are difficult to obtain and even when the line has been damaged it has been repaired again within twelve hours. No, it needs more drastic measures to put it completely out of action. That tunnel has got to be utterly destroyed so that it will take them months to clear it.”

“I see,” said Rex slowly, “and how do you propose to do that?”

“By placing a charge of high explosive inside the tunnel and blowing it up,” replied the Major softly.

“That doesn’t sound easy to me,” answered Rex soberly.

“It isn’t,” agreed the Major, “but H.Q. have said it’s got to be done, so done it must be. The only possible way is for a machine with a determined crew to land at night behind the German lines. They will have to get through the sentries, place the charge in position, fire it and then escape—if they can.”

“If they can?” echoed Rex.

“Precisely. Provided the tunnel is destroyed the rest is of secondary importance.”

“Sounds cheerful, I must say,” said Rex grimly. “You don’t mind what happens to the people as long as the tunnel goes West?”

The Major nodded. “I am afraid that is the way we have to work,” he replied. “Naturally, we are always delighted to see our operatives return, but the success of their mission is of greater importance.”

“Quite,” agreed Rex, “I see that. Well, when do we go?”

“Then you’ll have a shot at it?”

“I’m game—what about you, Tony?” queried Rex.

Tony looked pained. “If it’s good enough for you it’s good enough for me,” he replied briefly.

“Good. Then come and see me in the morning and we’ll settle the details,” said the Major, rising. “Not a word to anyone. It is, perhaps, hardly necessary for me to say that absolute blind secrecy is essential. One word and the enemy will know about it. Their operatives are as active as ours. Good night.”

The Major left the room abruptly.

“Well, what do you think about it, Tony?” asked Rex as the Major departed.

“It sounds a pretty deadly business to me,” grinned Tony, “but we’ll have a stab at it. Come on, let’s get to bed.”

The following afternoon found them arranging the final details of the plan with Major Trevor in his office at Wing Headquarters, which were situated at Neuville, not far from their own aerodrome. Plans and aerial photographs littered the table.

“Well, I think that’s about all,” observed Rex, picking up his cap. “To-night it is. We shall leave at eight o’clock. I’ll bring the Bristol over in daylight and land her outside”—he indicated the recently-abandoned aerodrome through the window. “It’s handy having a landing-ground so close to you, sir.”

“It is,” agreed the Major. “This room used to be 231 Squadron office, you know.”

“Yes, I remember it well,” replied Rex, “I’ve landed here many times. Well, come on, Tony, let’s go and get the machine; and you’ll have the fireworks ready for us when we return, sir?”

“I’ve got a couple of Royal Engineers making up the charge now, in the end hangar.”

“Good enough, sir,” replied Rex. “Come on, Tony, let’s go.”

Rex sat silent for some time, deep in thought, as they sped homewards in the Headquarters’ Crossley tourer. “I don’t quite see why he is so keen for us to land at that field he had marked out,” he mused. “I know it’s a bit bigger than the one we had decided upon, but it’s farther away, and I’m sure I could get down in the other one fairly comfortably. I’ll see how the wind is. In any case the surface of the field is an absolute gamble.”

“Well, it’s only a matter of opinion after all,” commented Tony. “I suppose we can land where we like when all is said and done.”

“Yes, we’ll see what it looks like when we get there.”

Arrived back at the aerodrome they had their tea under the banter of other officers who were curious to know what was in the wind, but to their enquiries Rex only replied with an enigmatical smile.

“Come on, Tony,” he said at last, “let’s be getting away,” and a few minutes later they were roaring through the still evening air on their short hop to the Headquarters aerodrome. Leaving the engine ticking over they made their way to the end hangar where two Royal Engineers were mounting guard over a neat, but bulky package. Rex whistled softly as he felt its weight.

“My sacred aunt,” he muttered, “this weighs a bit. How much?” he added, turning to the Engineers.

“Fifty pounds, sir,” replied one of the men whose sleeve bore a Lance-Corporal’s stripe.

“Holy mackerel, I’d no idea it would be so big. Somebody has got to carry this best part of a mile. It’s an awkward shape to get into your cockpit, isn’t it, Tony?” asked Rex.

The observer nodded. “I should think it would have been better in two parcels,” he agreed. “Moreover, we could then have split the weight and carried half each.”

“Could you make it up into two parcels?” Rex asked the Engineers.

“Of course, sir,” replied the Corporal. “Major Trevor has been down here helping us to get ready, but I expect it will be all right. Two packages means re-wiring and detonating; take about half an hour, sir.”

“All right, go ahead, I’ll give you a hand,” answered Rex. “This is the wire, eh?”

“Yes, sir. About a quarter of a mile of it. This end is fixed in the charge and then you unroll it as far as it will go. To explode the charge all you have to do is to connect these two terminals.”

The half-hour soon passed and the two packages were carefully stowed away. The airmen took their places in their cockpits. Little tongues of flame licked out of the exhaust pipes as Rex opened the throttle slightly and prepared to taxi into position for the take-off.

Tony leaned over, tapped his pilot sharply on the shoulder, and pointed. A figure was hurrying towards them in the darkness.

“Is that you, sir?” called Rex, throttling back.

“Yes.” It was Major Trevor’s voice. “Got everything you want?”

“Yes, sir.”

“Off you go, then. Remember the moon rises at nine o’clock; it’s now eight-thirty. Good-bye and good luck.”

He shook them both warmly by the hand and backed away from the swirling slipstream as Rex turned into the wind.

The night was shattered by a mighty volume of sound as he opened the throttle wide, and the next moment they were off the ground, climbing swiftly for height into the starry sky. A finger of gleaming silver stabbed the darkness not far away, another, and then another. Dash-dash-dot-dash flashed the nearest searchlight, using the Morse code. It was the signal letter of the night. An orange flame leapt into the sky ahead of them—the warning archie-burst of the anti-aircraft batteries which were working in conjunction with the searchlights. The searchlight had asked for the password. Tony took his Very pistol from his pocket and, leaning over the side of his cockpit, fired upwards into the night. A green ball of fire, changing slowly to yellow, glowed in the darkness. It was the “colour of the night” and his reply to the gunners below. O.K., O.K. flashed the searchlights, and then flickered out in their swift, curious manner.

Ten thousand feet glowed on the luminous dial of Rex’s altimeter, but still he climbed. Twelve, fourteen, fifteen thousand showed in turn, and then they headed for the lines. For ten minutes, still climbing, the pilot groped his way through the inquisitive searchlight beams, and then, when his altimeter registered eighteen thousand feet, he throttled back and eased the stick until they were planing gently almost at stalling speed.

Far below them a thousand flickering fireflies showed the course of the trench system which stretched from the North Sea to Switzerland, where a million men were engaged in a titanic life and death struggle. Far away to the north, a cluster of dull, glowing archie-bursts and a group of searchlight beams showed where night-bombers were at work. Almost silently they slid through the night, Rex peering ahead and downwards to pick up his landmarks. If possible he wished to land without opening up his engine again, for this would inevitably betray their whereabouts to the watchers below. For this reason they had climbed to the tremendous altitude which should enable them to glide far into the enemy country without using the engine.

Of the desperately dangerous nature of their task they had no delusions. A bad landing would mean that at the best they would remain in captivity until the end of the war. It might possibly explode the terrific charge of high explosive which Tony was carrying in his cockpit. Yet the landing was only the beginning of their difficulties. Rex thought no farther. “Let us have one thing at a time,” he muttered to himself, as he peered intently into the night.

Below them the earth was wrapped in profound darkness, the roads showing dimly as pale ribbons snaking across the war-stricken landscape; the woods lay like dull black stains. They were soon down to ten thousand feet as they lost height steadily on the long glide. Once a probing searchlight beam swept past them, paused in uncertainty as the light reflected on wings and struts, but passed on as Rex slipped away swiftly, sacrificing valuable height in the sideslip. The pilot, still peering downwards, altered his course a trifle, and, turning to Tony, pointed with outstretched finger. The words “the railway” floated back on the slipstream. Lower and lower they dropped until Rex was swinging in wide circles over a large field that lay below. He was tempted to switch the engine off altogether but dare not take the risk in case he overshot or undershot the landing-ground. The last thousand feet of height disappeared quickly and a row of trees loomed up ahead. With the wind moaning and sighing through struts and wires they slid gently over them and into the field. The wheels bumped gently once—twice; the propeller stopped as Rex switched off and they ran slowly to a standstill on the dewy turf. For a moment neither of them moved; but sat listening intently, peering with straining eyes into the darkness around them. “I think it’s all right,” said Rex softly at last.

“This is the field you wanted to land in, isn’t it?” asked Tony as he climbed stiffly from his seat.

“It is,” replied Rex tersely. “It’s plenty big enough. There was no point in going on to the other. Come on, get under her tail and we’ll pull her into the shadow of those trees; she’ll be facing what little wind there is if we have to get off in a hurry.”

Slowly and laboriously they dragged the Bristol into the black shade of a group of trees on the edge of the field. Tony carefully lifted the packages from the plane and laid them gently on the soft earth.

“Well, here we are,” said Rex quietly. “Seems funny to be in Boche territory, doesn’t it?”

“Funny!” whispered Tony. “I don’t call it funny.” He did not say that his heart was thumping so loudly that he wondered why Rex had not noticed it.

“I know what it feels like to be a burglar now,” whispered Rex as they each picked up a package and crept quietly along the side of the hedge. “Come on, this way. I’ve studied photographs of this area until I know the place by heart. It wouldn’t do to strike matches to look at a map.”

For a quarter of an hour they made steady progress, halting to peer cautiously round corners and to listen to the sounds that came faintly through the still night air. They could still hear the distant thunder of the guns along the line, and once the shrill cry of a nighthawk near at hand made both their hearts miss a beat. They crept through a gap in the hedge and came out on a road. The steady tramp of marching men came to their ears and they wormed their way back into the undergrowth and lay silent, hardly daring to breathe, until the steel-helmeted figures, which they could see silhouetted against the skyline, had passed by and disappeared again into the distance. They crossed the road and entered a stubble field.

“This is it,” breathed Rex. “The southern entrance of the tunnel is in the far corner of this field. Keep your eyes skinned for sentries.”

Once more they crept along slowly and with infinite pains, stopping every few steps to listen. Their goal was less than fifty yards away now and the strain became almost unbearable. At every step they expected to hear the sharp challenge of a sentry and see the flash of his rifle as he fired. Rex stopped and wiped the perspiration from his face, thankful that they had left their heavy flying-coats on the machine. He stopped suddenly.

“Sh-h-h!” he breathed, and together they sank silently to the ground. Someone was coming their way. The footsteps were approaching along the very hedge by which they were lying and with one accord they both squirmed into the thick brambles that bordered it.

“Is that you, Fritz?” called a voice in the darkness from somewhere near at hand.

“Ja, ja,” replied another voice so close that the two hidden airmen instinctively flinched. A figure detached itself from the hedge not ten yards in front of them and Rex saw that, but for the approach of the man behind them, they must, in another few steps, have walked straight into him.

“Come on,” called the first voice roughly, “you’re five minutes late.”

“No, I am on time,” argued the other.

Tony bit his lip as the heel of the man’s heavy boot came down on his hand, but he made no sound.

“There is bread, sausage and coffee at the box—don’t eat it all,” went on the voice. “I’m not looking forward to four hours in this miserable hole of a place. Who is likely to come here, I should like to know?” he grumbled on. “The Oberleutnant must have a bee in his bonnet.”

“Better not let him hear you say so,” said the other nervously.

For a minute or two the silence was broken only by the sound of a rifle being loaded. “Oh, well, the war can’t last for ever,” said the first voice. There was a gruff “gootnacht” and the sound of footsteps receding through the stubble into the darkness.

For another five minutes that seemed like eternity the two boys lay still as death, then Rex moved his hand very slowly until it found Tony’s face. By twisting his body slightly he could just place his mouth near his companion’s ear. “I can’t stick this much longer. I’m getting cramp,” he breathed.

“Where is he?” came back faintly from Tony.

“About ten yards down the hedge.”

“What’s he doing?”

“Nothing. He may stand there for hours. Don’t move.”

Then for Rex began an ordeal which was to haunt him for many a day. Many times in the future was he to wake up dripping with perspiration from stalking a silent sentry whose head he could just see against the moonlight on a railway embankment.

The work on hand must be done silently he knew. One sound and they were lost. With the muzzle of his revolver gripped in his right hand he wormed his way inch by inch towards the unsuspecting man. When he was almost within striking distance the German strolled casually a few yards farther on, and he had to begin all over again. At last he lay almost at the man’s heels, and then luck turned in his favour. The sentry yawned mightily, unfastened the collar of his tunic, stuck the bayonet of his rifle in the ground, took off his helmet and placed it on the butt. As he did so Rex rose up like a shadow behind him and brought the butt-end of the revolver crashing down on his unprotected head. The sentry sagged at the knees and crumpled up on the ground without a sound. Rex turned swiftly as he fell, and snatching up his package with a whispered, “Come on,” disappeared like a wraith in the direction of the embankment.

“What’s the time, Karl?” called a voice loudly from the other side of the embankment.

“Nine-fifteen,” replied Rex instantly, imitating the fallen man’s gruff voice tolerably well.

“Donner Blitz! How slowly the time goes,” growled the voice in the darkness.

Again the boys lay still while the man opposite strolled up and down humming softly to himself. Tony laid a trembling hand on Rex’s arm. “Let’s get it over,” he gasped weakly, “I can’t stand much more of it.”

Rex cupped his hands and put his mouth near Tony’s ear. “Give me your bundle,” he whispered. “Don’t move, but if he speaks, answer. If you hear a row start, sprint for the machine. I’ll get back to it somehow. Cheerio.”

“Cheerio!” breathed Tony, and the next second he was alone. Somewhere in the distance a train whistled shrilly and he wondered if Rex had heard it. The rumble of an approaching train soon became dimly audible and he listened in an agony of apprehension.

“Here she comes!” called the voice opposite. “More ammunition for the boys!”

“Ja, ja,” grunted Tony.

“What’s the matter with you to-night, Karl, you sound as bad-tempered as a bear?” came the voice again.

“So would you be with a cold like mine,” replied Tony through his nose, and added colour to his statement by sneezing violently in his handkerchief.

The train was less than a mile away now, roaring through the night. A black figure arose at Tony’s side and caught him by the arm. It was Rex. “Come on,” he gasped, “now’s our time; the noise of the train will cover any row we make.”

They hurried down the hedge, unrolling the wire as they went. They were a bare hundred yards from the embankment when a rifle blazed into the darkness. Rex knew instantly what had happened. The man he had stunned had recovered consciousness and fired his rifle for help. There was a shout of alarm followed by several others just as the train plunged into the far end of the tunnel. “This will have to do,” grunted Rex, dropping on to his hands and knees. For a second or two he fumbled with the terminals and then held them together.

Instantly it seemed as if the end of the world had come. A blinding sheet of flame leapt upwards. A reverberating roar rose to the heavens and a blast of air swept Tony off his feet. The earth rocked about him as he struggled to rise. “Come on,” cried Rex, “run for it!” and together they sprinted down the hedge. The gap which opened into the road loomed ahead, and as they sprinted across it they had a fleeting glimpse of running figures farther down. Panting and gasping for breath they halted as they reached the machine; a great noise of shouting, punctuated with minor explosions, came from the direction of the tunnel.

“It sounds as if they are getting excited,” grinned Rex as he put his hand on the radiator of the engine. “Thank goodness she’s still warm. Swing the prop. Switches off.”

“Suck in.”

“Suck in.”

There was a swishing noise as Tony frantically dragged the heavy propeller round to suck the gas into the cylinders of the engine. “Contact!” he yelled, casting concealment to the winds.

“Contact!” echoed Rex, and there was a shattering roar as the engine burst into palpitating activity. Tony dashed around the wing-tip, made a flying leap for his cockpit as the machine began to move forward, and fell headlong inside.

There was a yell of alarm, and the flash of a rifle shot stabbed the darkness in the direction of the road. Rex bared his teeth in a mirthless smile and shoved the throttle wide open. The Bristol sped across the turf like an arrow; for a moment he held her down and then pulled up in a swift zoom. At a thousand feet he flattened out and breathed freely for the first time since they had landed on German soil. Tony touched him on the arm and pointed downwards. “We brought it off!” he yelled above the roar of the engine—“Look!”

Rex looked down and caught his breath. Below them was a great crater from which blue and orange tongues of flame were leaping. “We caught the ammunition train—it blew up,” he bawled as he turned his nose towards the line.

Tony nodded dumbly. A searchlight appeared like magic in front of them and Rex banked steeply to avoid it. Another and another finger of white light pierced the darkness until the air around them was alive with the gleaming, probing beams; archie-shells glowed redly and filled the air with flame and hurtling steel. Rex dodged and twisted like a wounded snipe as he tore towards the lines. “Phew!” he gasped as he put his nose down for the final rush. “I shan’t be sorry when I’m out of this.”

The desolate waste of no-man’s-land lay below them now and he levelled out as the barrage of hate died away behind. The British searchlights sprang up to meet them, but Tony’s Very pistol and the “colour of the night” satisfied them, and they disappeared as swiftly as they had arisen.

Ten minutes later they slid quietly to earth on their own aerodrome at Maranique. “Well,” exclaimed Rex bitterly as he switched off and the noise of the engine died away, “I’m not opposed to a little excitement once in a while, but if that is a sample of a ‘secret mission,’ I’m all out for ordinary dog-fights and a quiet life.”

“Get out,” jeered Tony, “you know you’ve thoroughly enjoyed it. Come on, let’s ring up the Major.”

They walked quickly towards the mess where several officers were standing in the open doorway, no doubt wondering at the late arrival. “It’s all right, chaps,” replied Rex in answer to several questions. “We’ve only been doing a bit of night-flying practice—haven’t we, Tony?”

“That’s all.”

As they reached the mess door a touring-car pulled up and a figure alighted. It was Major Trevor.

“So you got back all right?” he asked rather breathlessly.

“Quite O.K., sir, thanks,” laughed Rex. “It wasn’t easy, as you said, but——” he leaned forward—“we’ve blown the tunnel sky high,” he whispered.

The Major looked at him hard for a moment, then seized his hand and gripped it warmly. “Good boy,” he said, “I’ll see H.Q. know who did the trick.”

Rex and Tony sat sunning themselves on the tarmac, feeling in fine form after a successful two-and-a-half-hour patrol, for Tony, from the rear cockpit, had shot down a Fokker that was out looking for easy meat, but caught a tartar instead.

An orderly-room clerk came hurrying along from the squadron office.

“Captain Lovell, sir,” he called.

“Yes, what is it?” replied Rex with interest.

“Major Trevor would like to see you, sir, he’s in the squadron office with the C.O.; and will you bring Mr. Fraser with you, sir.”

Rex nodded. “I wonder what’s in the wind now,” he said in a quiet aside to Tony as they made their way towards the office. Major Trevor looked up with a smile as they entered the room.

“ ’Morning, Lovell—’morning, Fraser,” he called cheerfully. “I’ve just been having a word with your C.O. about you, and I’d like to have another chat with you. I have told the C.O. what is in my mind so it is quite all right, if somewhat irregular. I think, if you don’t mind, we’ll go across to H.Q. because we may be some time.”

Major Lukers nodded. “Certainly,” he said, and then turning to Rex and Tony. “What Major Trevor has to say to you is with my entire approval, although naturally I should like to make it clear that I should be extremely sorry to lose two of my best officers. Nevertheless, you must do as you think best. You will understand what I mean when you have had a talk with Major Trevor.”

The two boys entered the Major’s car and were soon speeding down the road towards Neuville. Not a word was spoken during the journey, and Rex, seething with curiosity, was glad when they reached their destination.

“Now I am going to be as brief as possible,” began the Major when they had settled themselves down in his office. “I have a proposition to make. I was very much impressed by the way you carried out that raid the other night; it showed resourcefulness and ability. General Fellowes, who, as you no doubt know, is in command here, is delighted about it, and I may say at once that the scheme I am about to put up to you is made with his full approval. This is the Headquarters of the Intelligence Staff on this particular sector of the front, and our business is to find out by every means at our disposal what the enemy are doing. More than that, we endeavour to prevent enemy agents from finding out what we are doing. Without mincing matters, I can tell you that espionage, or spying, to use a more simple word, does not end there. It includes counterespionage, which means spying on the enemy’s spies, and that is the most deadly dangerous work in the world. Operatives—as we prefer to call them—know that if they are caught they will be shot, quickly, and without hope of reprieve. They are disowned even by their own side. Consequently, as they have everything to lose, they are desperate men, and in their ranks are some of the cleverest brains in the war—working without hope of honour or reward. In the first part of our duties we have been successful, but in the latter, well, not so successful. Briefly, information is leaking through to the enemy in a manner which clearly points to a highly-organised spy system within our lines. You must understand this. It is not easy for an operative to obtain information, but that is perhaps the simplest part of his task. It is far more difficult for him to pass that information back to his own side when he has obtained it. The enemy are not only obtaining valuable information, but that information is back in Germany within twelve hours; we have proved that beyond all doubt. There are many methods employed to convey information, carrier pigeons, and so on.” The Major paused for a moment to let his words sink in.

“For instance,” he went on slowly, lighting a cigarette, “the other night we put a net across the stream that runs near your aerodrome. As you know it flows from France into Germany. We caught some funny fish—such as bottles, carefully corked, with letters inside. Most of it was amateurish work, however, and did not help us much. The time has come when we must identify and isolate the group of expert agents who are working over this side. After a good deal of consideration we have come to the conclusion that the enemy must be employing aircraft on a fairly extensive scale. Well, we think, and you will probably agree, that there is only one thing to stop aeroplanes, and that is—aeroplanes. The reason why I have brought you here to-day is to ask you if you would be prepared to work exclusively for Headquarters, to try and locate these machines?”

“What exactly would you want us to do, sir?” asked Rex slowly.

The Major shrugged his shoulders. “Frankly, I do not know. You would have to take whatever steps you considered likely to produce results. I think I ought to warn you that tasks may arise which may be distasteful to you, but against that you must bear in mind that you would be doing work of the greatest possible importance, work demanding an even higher degree of skill and courage than that demanded by ordinary routine at a Service squadron. For the present you would simply have to watch, using your eyes and putting two and two together if you saw an aircraft behaving in a suspicious manner. Call yourselves flying detectives, if you like,” he smiled.

“Apart from the other night, may I ask if there is any reason why you selected us for this work, sir?” asked Rex.

“You may,” replied the Major at once. “It is because of your knowledge of the German language.”

“How is that going to help us?” queried Rex raising his eyebrows.

The Major pulled his chair a little closer. “I am just coming to that,” he said slowly, dropping his voice to a mere whisper. “You remember the Hannoverana you shot down the other day?”

Rex nodded. “Perfectly,” he said.

“Well, it is still here and it is in good order,” answered the Major with a curious expression on his face. “An occasion might arise when that machine could be used to advantage; you see, in an emergency, you could both pass as Germans.”

“Not in these uniforms,” smiled Rex.

The Major looked him squarely in the eyes. “The exigencies of war demanded that when the crew of the Hannoverana left their machine here, they left their uniforms as well,” he whispered significantly.

“Are you suggesting that we wear German uniforms, sir?” said Rex curtly.

“No, no, not necessarily—not as a regular thing of course,” replied the Major quickly. “I said in an emergency. One never knows what is going to turn up at this game. I know the idea is unpleasant, but somebody has to do it, and officers much senior to you, both of the fighting and diplomatic services, have much worse things than that to do in the service of their country. Still, if you prefer it, we will forget all about the German machine; but you must remember that it is up to every one of us to do his very best in his country’s service, whatever sacrifice it might involve.”

“If we were captured dressed like that we should be shot as spies,” broke in Tony aghast.

“Without the slightest doubt,” answered the Major coolly, “but there are dozens of men taking that very risk to-day. Nearly every night operatives are taken over the line on special missions, locating big guns, ammunition dumps, and so on. Usually they are flown over by selected night-flying pilots; the operatives themselves are disguised as peasants or German soldiers. If one of those machines was captured, either as a result of a forced landing, or for any other reason, both of the occupants would be shot. An officer’s uniform would not save him if he was carrying a professed spy. You may even have to undertake that sort of work. Now, what do you say, will you join us or not? It absolutely rests with you. I do not wish to force you in any way. Oh—and if you do join us, you will both remain on the strength of your present squadron.”

Rex looked at Tony. “Well,” he said, “what do you say?”

Tony shrugged his shoulders. “If we can do more good by working as the Major suggests than we can by ordinary routine-work, I think it is up to us to do it. Major Trevor seems to think we can. I’m not very keen on this business of flying under false colours, though, and I should never shoot at an enemy machine from a German plane. It’s hitting below the belt, and I cannot recall that even the German flying people have ever been guilty of that,” he declared.

“Good,” said the Major rising, “let us settle the details. I think you had better use this aerodrome as much as possible in case I need you, although in the ordinary way you will refuel and get your machine looked after by your own mechanics as before. I will arrange for you to have carte blanche and see that you are not detailed for any duties by your own Squadron. For the present I can only suggest that you fly where you like and keep your eyes open for aircraft behaving in a suspicious manner. Keep a sharp watch for possible landing-grounds, particularly this side of the line. Report to me if you want anything or if you discover anything requiring assistance. Good-bye and good luck!”

The Major turned towards the pile of correspondence and the boys departed with very mixed feelings.

“I don’t know quite what to think about this business,” began Rex with a worried frown after they had closed the door behind them. “It is either going to be pretty dull, or else——”

“I’ve got an idea that it’s going to be ‘or else,’ ” interrupted Tony. He little knew how true his words were to prove.

From eighteen thousand feet above no-man’s-land, Tony, leaning against the Scarff mounting of his twin Lewis guns, surveyed the sky slowly in every direction. Inch by inch, section by section, above and below, his eyes probed the atmosphere for a hidden menace. He knew that death, sudden and swift, might be the penalty for one moment’s carelessness. Far to the east a squadron of D.H.4’s were making heavy weather against a head wind and a furious bombardment of anti-aircraft fire as they returned from a bomb raid. He turned again to the west and squinted long and carefully between his outstretched fingers into the glare of the evening sun. The sky was empty of hostile machines.

It was nearly a week since they had begun their new duties and they had found absolutely nothing that could possibly be construed into a suspicious action. Except for a few unavoidable dog-fights the days had been uneventful. They had been told to avoid combat if possible, and Rex in particular was beginning to resent the enforced absence of action.

“Hullo—what’s that?” Rex had wobbled his planes slightly and was pointing with outstretched finger, and Tony crouched low as he peered at a tiny speck that had become visible high over enemy territory. It was still too far off for its nationality to be distinguished and Rex altered his course a trifle towards it, ready for anything that might arise. A cloud of black smoke blossomed out in front of the Bristol, another and another. They were over the German lines now and salvo after salvo of archie screamed up to them as they edged still farther in with their eyes on the stranger. The speck rapidly grew larger and Rex turned to Tony with a grimace of disappointment as it revealed itself to be a British machine—an S.E.5.

He’s got a bit of a nerve cruising about by himself so far over the line; what does he think he’s playing at, anyway, thought Rex. Twice since they had first seen it the S.E. had done a tight spiral turn, coming out on its original course. Rex flew closer, turning as he did so, and presently the S.E. and the Bristol were flying side by side back towards the British lines, the pilots waving light-heartedly to each other from time to time. Reaching the lines the S.E., after a parting wave, turned away on a new course and was soon lost to sight in the distance. Rex resumed his solitary patrol. For a few minutes he flew aimlessly up and down the line and then, after making a sudden signal to Tony, cut off his engine and dived steeply in the direction of their home aerodrome at Maranique.

“What’s the idea?” exclaimed Tony as the machine ran to a standstill. “I thought you said you were going to cruise until it was dark.”

Leaving his engine ticking over Rex leaned far back out of his cockpit and nodded. “Yes,” he said with a puzzled expression, “so I did, but did you see that S.E.5?”

“Of course.”

“Did you get his markings?”

“Yes, two eccentric white bars aft the ring markings. That’s 91 Squadron at Tourville, about twelve miles farther north,” replied Tony.

“Did you spot his number?” asked Rex.

“Yes, F-1743.”

“I thought that was it, but I wasn’t certain,” answered Rex. “I think I’d like to go to Tourville,” he went on with a mysterious smile. “Hold tight!” He pushed the throttle open and took off again into the evening sky, much to the surprise of the mechanics who had run out to guide the machine into the hangar.

They were not long in reaching Tourville. Several officers were standing on the tarmac and they watched their unusual visitor with interest. Rex taxied in, switched off his engine, and climbed out of his cockpit, Tony following. “Hullo, chaps!” he greeted the lounging officers as he unstrapped his helmet, “have you got a fellow here named Treeves—Bill Treeves?”

A youth, wearing the three stars of a captain, came forward and shook his head. “Never heard of him,” he said.

“Oh, I just wondered,” replied Rex casually. “He is an old pal of mine and I know he is in an S.E. squadron somewhere about. Well, how’s things?”

“Oh, so, so,” responded the other. For a few minutes they talked of dog-fights, the new German circus opposite, the British high-performance scout that was always coming out, but never did, and other trivialities of professional interest, but while they were talking Tony noticed that Rex was carefully taking stock of every S.E. on the tarmac.

“By the way, is your E.O. (equipment officer) about?” asked Rex suddenly.

“Yes, I think he’s in the squadron office,” was the reply.

“Thanks, I’ll go and have a word with him,” nodded Rex with a beckoning gesture to Tony, and together they walked briskly to the group of buildings at the end of the hangars. As he expected, Rex found the Equipment Officer in the squadron office talking to the C.O.

“Pardon my butting in, sir,” he began, “but have you a machine on your strength numbered F-1743?”

The Equipment Officer raised his eyebrows. “No,” he said slowly, “but we had until about a month ago. That was the number of Hooston’s machine, sir,” he said, turning to the C.O. “He went West on a balloon strafing show and is reported ‘failed to return’ in the records. What made you ask that?” he said suddenly, turning again to Rex.

Rex hesitated for a moment. “Oh, an S.E. with that number on and with your Squadron markings got me out of a tight corner. Just about a month ago it would be, and I thought I’d drop in and thank him. I’m sorry to hear he’s gone West—bad show. Sorry to have troubled you—thanks very much—good-bye—good-bye, sir.”

The two boys saluted and returned to the Bristol. “Come on, laddie, let’s get a move on,” said Rex briskly, “it will be dark before we are home if you don’t hurry.”

“Wait a minute, I don’t get the hang of all this,” protested Tony.

“Wait till we get back and I’ll tell you,” replied Rex crisply as he climbed into his cockpit. A mechanic sprang to the propeller and a few seconds later they were in the air again on the return journey to Maranique.

Back in their quarters, after some hot tea and toast, Rex proceeded to explain his action. “Now listen, Tony,” he began, “you remember seeing that S.E., it must have been five miles over the line when we first saw it.”

Tony nodded.

“Did you notice anything funny about it?”

“No, I can’t say I did.”

“Neither did I until after he had gone, and then I remembered that we didn’t see any archie near him, which was a very odd thing. We were being archied like stink at the time. Why wasn’t he being archied, that’s what I want to know. And did you notice that as soon as he joined us archie faded out completely?”

Tony looked at Rex with an expression of enlightenment creeping over his face. “Great Scott! you’re right,” he said, “and I never noticed it.”

“Well, I didn’t realise it at the time, but after we turned away they started archie-ing us again and then it suddenly struck me. It was a bit queer to say the least of it,” went on Rex. “And then, did you see him doing those turns for no apparent reason? Thinking it over, it occurred to me that it might be some sort of signal to the gunners not to shoot, but why should a British machine signal to German gunners? I decided to slip home and have another look at that bird if I could find him,” concluded Rex grimly.

“Who is Bill Treeves—the chap you asked for when we landed on the S.E. aerodrome?” asked Tony.

Rex made an impatient gesture. “Goodness knows, I don’t,” he grinned. “I’ve never heard of him in my life, but I had to make some sort of an excuse for landing, hadn’t I? I couldn’t just land on somebody else’s aerodrome and pry about without so much as a ‘by your leave.’ You were right about the squadron markings, but 1743 wasn’t there, as you saw, and I had a shrewd idea that it wouldn’t be, either. You heard the rest. That machine went down in Germany a month ago. Who is flying it now? Tony, it begins to look to me as if we are on the track of something fishy at last.”

“Where is that machine now, do you think?” asked Tony, a trifle pale.

“That’s what I should like to know,” replied Rex. “It’s down over this side of the line somewhere, but it would be like looking for a needle in a haystack this time of night. We may know something more about it to-morrow morning; the fellow who flew it, whoever he is, Hun or Englishman, is not likely to try a night landing in an S.E. unless he’s pretty desperate. It’s my experience that people stick to a course they know. We know pretty well where he crossed over and it is a thousand to one that he will go back the same way sooner or later. It may be to-morrow morning, and we shall be there to see if I’m right.”

“Suppose he does come, what are we going to do?” asked Tony. “We daren’t risk shooting down a British machine, anyway, not on the mere suspicion of fishy behaviour.”

“Good heavens, of course not; besides, what good would that do? We want a word with this pilot alive—dead men can’t talk. We’ll keep an eye on his movements and our actions will depend on what he does. Well, laddie, let’s get some sleep. Four-thirty in the morning suit you?”

“Suits me. Good night, old boy.”

*      *      *      *      *

The first streak of dawn found the Bristol fighter high in a sky of pale turquoise blue, heading for the scene of their encounter with the mysterious S.E.5. Below them the earth lay like a vast well of indigo and purple shadows. To the east the rim of the rising sun showed just above the horizon, tingeing their wings and struts with a brilliant orange glow. It was bitterly cold. Tony crouched low in the icy blast of the slipstream of the propeller as he searched the sky around for the machine they sought. Eighteen thousand feet ticked up on the altimeter and Rex snuggled a little lower in his cockpit. Once a high patrol of Sopwith Camels passed just below them, the leader waving a cheery good morning with his gauntleted hand as he scoured the sky for hostile aircraft.

A blossom of black smoke stained the turquoise blue sky not far away and warned them that they were on the edge of enemy country. Rex climbed until the machine reached its ceiling and then began casting around in wide circles.

“Here he comes!” The words rose involuntarily to Tony’s lips as his eyes suddenly fell on a gleaming speck far below. From their altitude it appeared to be crawling along the ground, but he knew from experience that it was not less than ten thousand feet above the desolate shell-torn no-man’s-land that lay below. A quick touch on the shoulder was sufficient to warn Rex that the quarry had perhaps been sighted and the Bristol changed its course to watch the stranger. Was it the machine they sought, or was it not? Rex had no means of knowing, and a close approach would certainly be sufficient to warn the pilot of the other machine, if he was the man they were after, to be wary in his actions. Still, it was unlikely that a scout would be heading out alone into enemy sky as the one below appeared to be doing. His actions would soon tell them if their surmise was correct.

Rex caught his breath sharply as a salvo of archie bracketed the lone machine. Instantly the pilot did a complete turn and continued on his original course. The archie faded away and no more took its place. Rex throttled back and commenced a flat glide in the wake of the other machine, hoping that he had not been seen. He had no desire to call attention to himself, though it was unlikely that they would be spotted at the height at which they were flying unless archie got busy, when the bursts would certainly attract the other pilot’s attention.

They were down to fifteen thousand feet now, well over the enemy’s side of the line, and Rex was beginning to feel anxious as he scanned the sky for hostile machines, while Tony continued to watch the S.E. as they had planned. An aerodrome loomed up ahead and Tony grabbed his map as he saw the other machine sinking rapidly towards it with the obvious intention of landing.

“He’s going down!” yelled Tony in Rex’s ear, and the pilot nodded.

“Keep your eye on him!” he bawled, and turning, headed back towards the British lines at full throttle.

“Did he land?” yelled Rex presently as they crossed into the comparative security of their own lines.

Tony nodded and then crouched lower in his cockpit as Rex nosed down in a steep dive. “What are you going to do?” he shouted as their wheels touched ground on the aerodrome at Neuville.

“Come on, I’ll show you!” snapped Rex tersely as he switched off and climbed stiffly from his seat. “We’ll beat this chap at his own game. I am going to fly over there in the Hannoverana.”

Together they hurried to Major Trevor’s office.

“No, sir, I’ve nothing to report,” said Rex quickly as the Major rose to his feet. “It’s just a hunch, that’s all. I want to use the Hannoverana.”

“It is in No. 3 shed,” replied the Major. “For goodness’ sake be careful,” he went on anxiously, “and don’t get shot down by our own people.”

“We shall have to chance that,” replied Rex. On the threshold he paused, and then slowly came back into the room. “We might as well do the job properly,” he announced, “where are those Boche uniforms, sir?”

Major Trevor handed him a black suitcase without a word. As Rex reached the door the Major called out to him, as if it was an afterthought:

“Whatever happens,” he said, “your lips must be sealed as to where you got those uniforms. That is part of our code.”

“Right, sir,” returned Rex crisply. “Come on, Tony.”

“My word, the Major is no fool,” said Rex as they took off their British uniforms and donned the others. “Have you noticed how he has had these uniforms altered to fit us—I expect he got copies of our clothing cards from the squadron. That’s what I call foresight, but that is why he is where he is, I expect. He seems to have thought of everything—papers, and even identity discs. Flying-coats, caps, goggles, the whole bag of tricks ready beside the machine. That’s pretty good. Our greatest danger lies in getting to the lines,” he went on as they walked over to the black-crossed machine. “By James, it would be no joke to be shot down by our own archie. Now! This is our plan.”

As the two airmen faced themselves a faint smile crossed their faces. “It is funny what a difference uniform makes,” observed Rex; “it gave me quite a shock when I looked at you then—you look exactly like a Hun.”

“I’m not sure that you aren’t one,” replied Tony grinning, “but seriously, just what are we going to do?”

“I am going to fly low down over that German aerodrome,” answered Rex slowly. “I might even land.”

“Land!”

Rex nodded. “It is taking a desperate risk, I know, but we are playing a desperate game. If we do go down this is our story. You are Ernst Koepler; I am Adolf Wistmann. Those are the names on the papers in our pockets. We are of the 97th Army Corps Squadron. We have got off our course and have landed to ask the way. Get that firmly fixed in your head. That’s all.”

“It sounds a feasible tale,” admitted Tony, “but I’ll tell you straight that this idea of landing gives me a funny feeling in the tummy.”

“I expect we shall get used to that,” said Rex in a matter-of-fact voice. “If there is any talking to be done you’d better leave it to me, although the less we say the better.”

The Hannoverana was not a difficult machine to fly, as Rex soon discovered when they were in the air. He did not head straight towards the lines because he knew that archie would be particularly bad there, but climbed to the limit of the machine’s performance, ready to dive for the line at a moment’s notice. Groups of white archie-bursts soon began to gather around them. At five thousand feet they were getting dangerously near, and Rex waited no longer. Turning towards the lines he roared across, still followed by the persistent gunners. He looked around to make sure that Tony was unhurt and smiled as the archie-smoke died away behind them.

Suddenly the smile gave way to an expression of puzzled surprise. Tony had grabbed his guns, but released them again with a gesture of utter helplessness. The rattle of a machine-gun reached his ears and he whirled sharply to ascertain the cause. A Camel was zooming up at them, its twin guns belching streams of orange flame. He understood Tony’s action at once. They were being attacked and they dared not shoot back. An ominous flack-flack-flack told him that the Camel’s bullets were ripping through the wood and canvas of the fuselage behind him. He flung the stick over and kicked out his foot in a vertical bank, and then sent a stream of tracer across the nose of their aggressor. The Camel swerved so violently that Rex suspected that the pilot was a man new to the game and prayed that he would not press the attack right home.

His hopes were without foundation, for the Camel pilot had evidently made up his mind that this was an opportunity not to be missed. Bullet holes through his planes showed Rex that the Camel pilot was making good shooting and he knew that unless something happened soon a bullet would hit one or the other of them. Tony was pouring burst after burst before and behind the scout. Once, indeed, he actually hit him as the Camel made its famous right-hand turn and dived straight through his line of fire before he could release the triggers. The Camel dropped a little farther behind, but did not relax the ferocity of its attack.

Help came from an unexpected quarter. A scarlet and black Fokker triplane dropped out of the sun and the Camel pilot was forced to engage an opponent likely to cause him more concern. The crew of the Hannoverana did not see the end of the combat, but seized the opportunity of getting away while the going was good and left the two scouts to work out their own salvation.

HELP CAME FROM AN UNEXPECTED QUARTER

Rex gave a startled cry of dismay as Tony turned and faced him. A bullet had ripped open the front of his coat, his goggles were smashed, and a tiny trickle of blood flowed down from under his helmet; but he breathed a sigh of relief as the observer held his thumbs up, the universal signal that all was well.

“Only a scratch—bit of glass!” he yelled, and Rex turned again towards the aerodrome that was their destination. Without warning the engine suddenly spluttered and died away; the propeller stopped revolving, and Rex looked anxiously ahead to see whether he would be able to reach the aerodrome.

“We’ve got to go down, anyway!” he yelled, and Tony nodded, understanding.

“Good job we’ve got these clothes on,” continued Rex, “and this should add colour to our tale,” he added, pointing to the signs of the conflict. In spite of the deadly nature of what lay before them they could not repress a smile. To be attacked by a British machine and rescued by a German was ludicrous. But Rex had little time for idle speculation. He reached the aerodrome with height to spare and made a neat, tarmac landing, notwithstanding the fact that he had to come in with a “dead” stick—as a stopped propeller is called.

“Are you all right, sir?” called a mechanic who had run out to meet them.

“Jawohl,” replied Rex instantly, dropping into his part.

There were expressions of wonderment at Tony’s narrow escape and they turned to examine the machine. It was soon ascertained that a bullet through the petrol tank had done the damage.

“How long will this take to put right?” asked Rex anxiously.

“An hour, perhaps more,” replied one of the mechanics.

“Good, hurry up with it,” growled Rex in the true German fashion as he turned towards the sheds. His eyes ran swiftly over the machines on the tarmac and in the hangars, but the S.E.5 was not among them. An officer strolled up to them.

“You’ve had a close one,” he smiled. “How did it happen?”

Briefly Tony described the combat. At the mention of the red and black triplane the German pilot’s eyes opened wide.

“You will be avenged,” he assured them. “That was von Ketner of the Jagdstaffel 7. He has fourteen victories already and he has only been at the front a month. But come in and have a drink while you are waiting,” he invited them. “My name is von Henkel.”

Unable to refuse they followed their host into a sparsely-furnished room with a long trestle table running down the middle. The German shouted an order and an orderly entered with three large mugs of beer.

“Prosit!” toasted the German, raising his glass.

“Prosit!” echoed the others.

Several more officers joined them and Tony had to repeat the story of their adventure. But Rex was watching a man in flying-kit who was seated at the far side of the room with his back towards them in earnest conversation with a German officer wearing the uniform of a Hauptmann (captain). He sauntered across to the window near them, ostensibly to look at the weather, for the sky was beginning to cloud over. Finishing his survey of the sky he turned and glanced casually at the man in flying-kit whom he was now facing. It was only a glance, but it showed him all he needed to know. The flying-coat was undone at the collar exposing a few inches of tunic—a British R.F.C. tunic!

Rex had barely rejoined the others when the two men from the corner walked over to them, but he noticed that the flying-coat was now buttoned at the throat.

“You’ve just had a combat, I hear,” said the Hauptmann.

Rex nodded. “Yes, sir, I got my tank holed,” he replied. He was scarcely able to restrain a sigh of relief when the two passed on, for at the back of his mind was a dim suspicion that he had seen the face of the man in the flying-kit before, but where, he could not remember.

“You had better ring up your squadron and tell them you are here,” said the Hauptmann over his shoulder.

“I think it is hardly necessary, sir, thanks,” replied Rex easily, “the machine should be ready by now and we shall be home in a few minutes.”

The Hauptmann nodded. “As you wish,” he said shortly.

“Come,” said Rex to Tony, “let us see if the machine is ready,” and after thanking their hosts for their hospitality, strolled along the tarmac to where the machine was ticking over, evidently being tested.

“She is all right, sir,” called an Unter-Offizier.

They climbed into their places, waved away the chocks, taxied into position and took off. The whole thing was done so easily and faultlessly that Tony marvelled at the very simplicity of it. Rex looked back over his shoulder grinning broadly.

“I always thought you were a Boche,” jeered Tony.

When they were halfway home Rex tilted his left wing down, and, beckoning to Tony, pointed to the ground. In the middle of a field, in the centre of a group of German soldiers, lay a torn and twisted plane. It was painted black and red.

“Von Ketner will score no more!” yelled Rex above the noise of his engine. “I hope that Camel pilot is satisfied with his dirty work and isn’t hanging around here or it will be a bad business for us!” he shouted, grimacing.

They reached the line without being molested, however, and raced through the inevitable archie to Neuville, where they landed and taxied quickly into the hangar. Ten minutes later they were once more in proper uniforms with their disguises carefully packed away.

“Well, that’s that,” said Tony with a sigh of relief, “what’s the next move?”

“To watch this S.E.5 bird, of course,” replied Rex, “we’ve got his game weighed up now. Once we find his rendezvous over this side of the lines we shall catch a queer basket of fish or I’m very much mistaken. We’ll keep an eye open for him over this side to-morrow, in the Bristol.”

“Are you going to tell the Major about this?” asked Tony.

“No, I don’t think so, not yet,” replied Rex thoughtfully. “I think we’ll keep what we’ve discovered under the hat until we have something definite to lay before him. It shouldn’t take long.”

They wheeled out the Bristol Fighter, returned to Maranique and spent the rest of the day quietly talking over their adventure.

It was about six-thirty when Pat MacLaren, their Flight Commander, put his head round the door of their room.

“Are you boys coming to Veleroy?” he grinned.

“Why, what’s on?” asked Rex.

“Guest-night. It should be a merry evening—the tender leaves in ten minutes if you want to come, and it won’t wait,” he announced, as he withdrew.

“What do you say, shall we go?” asked Rex.

“Fine,” replied Tony, “219 Squadron are at Veleroy; they’re a cheery crowd. They’ve got Camels.”

“Come on then, let’s get dressed,” said Rex briskly.

The tender with its rollicking party was soon en route, and half an hour later it pulled up with a screeching of brakes in front of the door of the Camel pilots’ mess. As they entered the room Rex and Tony looked around with interest to see if there was anyone there whom they knew; at Rex’s elbow a fair-haired lad, still in his teens, was talking rapidly to a group of interested listeners.

“—and he hit the deck with a devil of a bang,” he concluded amid roars of laughter.

“I hear you got the red-and-black Tripehound to-day, Tommy,” sang out a new arrival hurrying up to the group.

The Camel pilot nodded. “Yes, we’ve had one or two goes at it, but I got him to-day. It was a pretty close shave, though. I had chased a blinking Hannoverana halfway to Berlin and the Jerry in the back seat had shot a bit off my left aileron, which didn’t improve matters. He beetled off when the Tripe arrived. I was scared stiff when the other Hun butted in because I had to chuck my machine about and thought every minute the aileron would drop off. I had to take a chance on it, though——”

His voice trailed away as the group moved slowly towards the dining-room.

Rex nudged Tony in the ribs and chuckled. “So that was the lad who shot us up to-day,” he grinned. “I wonder what he would say if he knew that it was you who busted his ailer. . . .”

His voice died away into an inarticulate gasp. Tony, watching Rex’s face, saw it turn pale and an expression of incredulous amazement creep over it. He was staring straight over his, Tony’s, shoulder at something behind him, and Tony, swinging round and following his gaze, choked back an exclamation of astonishment. There, not five yards away, was the man whom they had last seen only a few hours before in the German mess.

Rex was about to drag Tony away, but before he could do so the door was thrown open and Major Trevor entered.

“Hullo, Fairfax,” he cried cheerily, “how are you?” and then catching sight of Rex and Tony, “Hullo, you boys, so you’re here, too, are you? You know Fairfax, I suppose?”

There was no avoiding it. Indeed, the whole thing had moved so swiftly that Rex had had no time to think, much less to act. Almost before the words were out of the Major’s mouth they found themselves facing the stranger.

“No, we haven’t met,” said Rex in a voice which he strove to keep steady, and as they shook hands Rex thought he saw a gleam of recognition leap into the other’s eyes.

“Pleased to meet you,” said Fairfax; “I seem to have seen you somewhere before, but I can’t think where.”

“Oh, probably at another guest-night somewhere,” replied Rex easily; “I’ve been dodging up and down the line for about six months now.”

“Ah, I expect that was it,” replied Captain Fairfax, turning to shake hands with Tony. Whether he recognised him or not neither Rex nor Tony were afterwards able to say; at any rate, if he did, he made no comment.

The entrance of an orderly to announce dinner saved what Rex well imagined might develop into a difficult situation.

“What are you going to do?” asked Tony as they seated themselves at the table.

“Keep an eye on him and speak to the Major at the first opportunity. Just look at him,” he went on, nodding towards Captain Fairfax, “he seems to know everyone. I suppose it isn’t possible that we’ve made a mistake.”

“No!” Tony shook his head emphatically.

“Well, it’s jolly awkward, to say the least of it,” continued Rex; “it’s all very well to say we’ve seen an officer over the lines, but it sounds a pretty cock-and-bull story, doesn’t it? We should look fools trying to put him under arrest, which is what we ought to do. We have only our word for it, remember, and what are we going to say about ourselves being over there? Dash it! when all is said and done Fairfax might just as well put us under arrest. Let us wait and see what the Major has to say.”

Immediately dinner was over Rex sought Major Trevor and took him on one side. “Pardon me, sir,” he said, “but can you tell me anything about Captain Fairfax?”

“Fairfax—why? Is he a spy?” smiled the Major broadly.

Rex grinned sheepishly.

“I should have thought you would have heard of Fairfax,” went on the Major, “he is a regular soldier and has been mentioned in despatches several times. He got the M.C. he is wearing for a particularly plucky show. He used to be a flight commander in 217 Squadron but he is at Divisional Headquarters now—one of the keenest officers in the Service.”

“I see,” said Rex slowly, absolutely nonplussed.

“What made you ask?”

“Oh, I only wondered,” replied Rex, feeling that he had made rather a fool of himself. “I seem to have seen him somewhere before. Now please take me seriously, sir. I suppose—er—er—well, er—I suppose he is absolutely beyond any possible suspicion of—er—espionage?”

“Good God, man, what are you talking about?” replied the Major angrily, “you must be crazy. What in the name of fortune made you say such a thing?”

“Only that I saw him sitting talking to Hauptmann von Rasberg, commanding the German staffel at Varne, in the officers’ mess there this morning,” replied Rex nettled.

Major Trevor took a quick step backwards as if Rex had struck him. For an instant he stared in open-eyed amazement, and then his surprised look gave way to one of amusement. He threw his head back and burst into a long peal of laughter. He laughed and laughed again until half the officers in the room were laughing with him. “Well, that’s a good one,” he said, wiping his eyes. “I’d love to tell him that, in fact I will—after the war.” And then he became serious again and put his hand on Rex’s shoulder in a fatherly manner. “I’m sorry I laughed like that,” he said soberly, “but really, the idea of Fairfax sitting in a German mess is too utterly preposterous. Why, his very record puts him beyond any possible suspicion.” He dropped his voice to a whisper. “So you landed in Germany to-day?”

Rex nodded.

“What did you find?” asked the Major, his eyes narrowing as his professional instinct was aroused.

“Nothing,” admitted Rex frankly, “except what I have just told you.”

“Well, I think you can forget that; faces are very much alike, particularly in uniform. Be careful,” he admonished him. “I should be the last man to discourage you from taking any step, however desperate, in your work, but I should be sorry to lose you.”

Rex looked up into the Major’s keen soldierly face and felt a glow of pride. While the British army possessed such splendid officers as Major Trevor they could not lose the war, he thought proudly.

Rex was awakened the following morning by the insistent summons of his batman. “Come along, sir, please,” called the ack-emma. “Fine morning, sir—Wing are on the ’phone asking for you.”

“What’s that you say?” asked Rex, as, with tousled hair, he scrambled wild-eyed from the bed. “All right, get me a cup of tea, I’ll be back in a minute.” He flung on a dressing-gown and hurried to the telephone.

“Yes? Lovell here,” he called. “What’s that—Oh, good morning, Major. Yes—yes—I will, sir—ten o’clock—good-bye.” He hung up the receiver, hurried down the corridor and awakened Tony who was still sleeping soundly. “Come on, laddie,” he called, “it’s late. The dawn patrol will be back before we are dressed and the Major wants us in his office in half an hour.”

“I wish you wouldn’t wake me up with a start like that,” grumbled Tony.

A hurried breakfast and they were on the tarmac warming up their engine before taking off. “If he wants any more tunnels blowing up, you can tell him to do his own blowing!” he shouted in Rex’s ear.

“Tell him yourself,” jeered Rex as he waved away the chocks. His fitter examined the sky in every direction and saluted briskly—the “all clear” signal. Rex glanced at the wind indicator, taxied out on to the aerodrome, and slowly opened the throttle; the versatile two-seater swung up over the sheds, and away in the direction of Neuville. When the abandoned aerodrome lay below Rex throttled back, sideslipped neatly over the hangars, landed, and taxied up to the shed which they had taken over for their own use.

“What do you think he wants to see us about?” asked Tony as they made their way to the Major’s office.

“I’ll be able to tell you better in half an hour,” replied Rex. “We shall soon know. Here we are.”

He tapped sharply on the door of Major Trevor’s office and in response to the curt, “Come in,” opened it and entered.

“Hullo, here you are, then,” said the Major. “Take a seat, both of you—I won’t be a minute.” He sealed a packet, rang for an orderly, and handed it to him. “Now,” he said when they were alone, and then paused as if uncertain how to begin.

“No more tunnels to be blown up, sir?” asked Rex with a smile.

“No, not exactly,” replied the Major seriously, resting his chin on his hand.

Rex started. “Not exactly. Something like it, eh?”

The Major nodded. “This is the position,” he said slowly. “I have a dangerous mission for somebody; unfortunately the pilot who would normally undertake it has—er—met with an accident which will prevent him doing it for me.”

“Walked into his prop. or something?” asked Rex, professionally interested.

“No,” replied the Major. “He went over the lines two nights ago and has not returned.”

“When are you expecting him?” enquired Rex.

The Major shook his head. “I am not expecting him,” he said grimly. “He was shot at dawn this morning at the back of the riding school in Lille.”

Rex reached for his cap. “Ugh,” he shuddered, “come on, Tony, this is no place for us.”

“Wait!” The Major held out a restraining hand. “Listen to what I have to say first. I do not think this mission is as dangerous as the one you have just done. Briefly, it consists of landing behind the German lines and taking a message to an address in Lille. That’s all. If you will do this for me, I shall be greatly indebted to you. If you will not, and I have no intention of pressing you, I must find someone else.”

“Tell me more about it,” said Rex slowly. “I doubt if you will find two people able to speak German as well as Fraser and I do, and this looks like an occasion when it will be a useful asset.”

“It will,” agreed the Major. “You would have to fly over after dark and land wherever you wish, although obviously it would have to be somewhere near Lille. You would go to an address I should give you, deliver a letter, wait for a reply, and then get back as soon as possible. One man might do it alone, although if both of you go one might remain by the machine while the other goes on alone to Lille. Two people make it easier to restart the propeller for the return journey, but that, of course, is your own affair. Your two greatest dangers are these. In the first place, you might land in a trap, and secondly, your machine might be found while you were away, in which case you would have to get back across the lines, or into Holland or Switzerland, as best you could, and that is no easy matter.”

“A trap—what sort of a trap?” asked Tony curiously.

“The Germans have a habit of putting strands of wire across fields in which an aeroplane might land. The result is, of course, that the machine crashes when landing. But if you seriously think of undertaking this mission,” went on the Major, “I think the time has come when in fairness to yourselves you should know more about the work on which you are engaged. Make yourselves comfortable, it will take a minute or two.” He took a fresh cigarette from the case in front of him and tapped it reflectively on the desk.

“In the first place, no mention is ever made of secret missions outside intelligence circles,” he continued, “and even then it is only touched upon when it is absolutely necessary. We know that the Germans made secret missions by air very early in the war and France soon followed suit. As a matter of fact, it was easier for France than it was for Germany, for this reason. After landing, a German agent found himself in France, a hostile country, with every man’s hand turned against him. On the other hand, a Frenchman found himself in his own country, or in Belgium, although the territory was occupied by the Germans, but he could always look for support to the peasants or working-classes who were still there. After all, they were his own countrymen and, of course, spoke his own language—another valuable asset. Secret missions soon became the order of the day and in an attempt to check them France was forced to take the public into her confidence. Listen to this.” The Major rummaged among some papers in a drawer and took out a printed slip. “This has been broadcast all over France,” he added:

“Well, that is clear enough and it shows how serious things must have become for the French authorities to publish it,” said the Major replacing the slip in the drawer. “The usual work of a special-mission pilot,” he continued, “consists of taking and landing in hostile territory a passenger whose duty it is to collect information of military value—the positions of guns, ammunition dumps, movements of troops, and so on. Sometimes the job is more specific, as it is in the present case, and the agent has to deliver a message or damage a structure of military importance to the enemy. The risks are obvious. If the agent is taken he is shot. A pilot caught landing one is also shot, and his uniform would not save him. Needless to say, only volunteers are chosen for this work, usually civilians who know the district well. I should send such a man with you to-night, Lovell, but for your knowledge of German and the fact that you two are comrades and derive a good deal of moral support from each other’s company. The pilot, having dropped his man, comes back home and the affair is finished, unless he has previously arranged to pick up his man again at a certain place and time. The agent usually takes with him carrier pigeons which he releases when he has any special information to impart. Finally, in case you think the work is infra dig., it may interest you to know that some of the most famous pilots in the French Flying Corps have volunteered and actually carried out special missions.” The Major dropped his voice.

“Vedrines and Navarre, both renowned pre-war pilots, and Guynemer, the famous ace, have all done their share of this work. Unfortunately the work of an agent is unknown to the world, and you can imagine the stoic spirit of self-sacrifice that is necessary. The man who gets killed in the fury of combat dies a soldier’s death; the man who faces a firing party against a blank wall in the cold grey of dawn, does not. Well, now you know more about the business, what do you say? Will you go?” concluded the Major.

“This is all very interesting,” said Rex after a moment’s pause, “very interesting indeed. Personally, I would rather be at a squadron, but as someone has to do the work and we happen to be particularly well equipped for it, well, I’m your man, Major.”

“And you will go to-night?”

“I will.”

“And you——?” The Major turned to Tony.

“Where Lovell goes, I go,” he said briefly.

“Then you had better see about your disguises,” said the Major rising and unlocking a cupboard and disclosing several suits of dirty clothes. “These are typical peasants’ rig-outs. You will attract less attention walking about Lille in these than you would in your own uniforms,” he added humorously.

Ten minutes sufficed for them to make their selection, while the Major wrote rapidly at his desk. He sealed the letter and handed it to Rex. “Be careful with that,” he warned him, “and obey the instructions I am now going to give you to the very letter. You will go to number eleven, Rue de la Concorde. It is a small side-turning off the Place de Ville, opposite a small church. You will find the door open. Enter and ring the bell which you will see on the table in the hall. Whoever comes to you will say, ‘What brings you here at this hour?’ and you will reply, ‘Fritz asked me to leave a message to say that he will soon be home.’ He will say, ‘When shall I expect him?’ and you will reply, ‘At ten o’clock.’ Ten is the password. It is the day of the month, and to-day is the tenth. He will ask you inside and you will give him the letter and wait for a reply. That is all. Any questions you would like to ask?”

“No, sir,” replied Rex, “I think that is all quite clear.” As he rose to his feet he thought he saw a shadow cross the window and he glanced up quickly. It was slightly open. He frowned and made as if to speak, but changed his mind. “I’m getting jumpy already,” he thought to himself half-angrily.

“Good-bye and the best of luck,” said the Major.

“Good-bye, sir.”

When the boys reached the front of the building an officer was standing on the runningboard of a staff Crossley touring-car outside. It was Captain Fairfax.

An exclamation rose to Rex’s lips, but he forced it back; instead, “Hullo, Fairfax,” he sang out, “what are you doing here?”

“Hullo, Lovell—’morning, Fraser,” cried Fairfax. “Oh, I’ve just brought D.D.R.O.s (Divisional Daily Routine Orders) over. Can I give you a lift back?”

“No, thanks,” replied Rex, “we are flying.”

“As you like,” replied Fairfax with a parting wave. “I’m afraid I’ve gone off flying these days. Cheerio.”

“Did you hear that?” said Rex as they walked down to the machine. “He’s gone off flying. Does he think he can take us in like that? Bah! I should like to know if it was he standing outside that window, though,” he added reflectively.

“Well, it wouldn’t be much use asking him,” observed Tony tritely.

It was lunch-time when they returned to Maranique.

“What had we better do now, do you think?” asked Tony, stirring his coffee reflectively.

“I think the best thing we can do is to have a look over the Bristol, get her refuelled, and then get some sleep,” answered Rex. “I can’t sleep in the middle of the day, but we had better rest, anyway; we shall need all our wits about us to-night if I know anything about it.”

“I think that’s a sound idea,” acknowledged Tony. “We will ask to be called at six; that will just give us time to settle details before taking off.”

A watery sun was sinking in the western sky as the two airmen, with their flying-kit over their peasant garb, made their way along the tarmac to the shed which housed their machine. The last patrol of the day was already home and the aerodrome was deserted except for a few mechanics who had been left to finish off odd jobs. Rex bent down and rubbed his hands on the muddy ground and put a smear or two on his face. “It isn’t much use wearing these rags if our faces look as if we have just stepped out of a bath,” he observed. “We might as well do the job properly.”

“Have you filled her up, Smyth?” he called to a mechanic, referring to the fuel tanks of the Bristol fighter.

“Full right up, sir,” replied the ack-emma.

“Good, get her out.” Half a dozen willing hands seized the machine and wheeled it out on to the deserted field. Rex and Tony took their places. “Switches off,” called the pilot. The mechanic turned the big prop. round several revolutions, and then, “Contact!” he called. There was a roar as the Rolls-Royce engine burst into sudden palpitating life; little tongues of flame shot out of the exhaust. Slowly the machine swung round as the mechanic hung on to a wing-tip and Rex opened the throttle in little short, sharp bursts.

The pilot raised his hands above his head. The mechanic released the wing, glanced up, saluted, and the Bristol roared away into the silent sunset.

Up and up they climbed in wide circles in order to have plenty of height before they passed over into enemy sky. Once or twice the searchlights flashed their gleaming challenge, but Tony replied with the “colour of the night” and the Bristol proceeded on its way unmolested. At twelve thousand feet, still climbing, Rex headed for no-man’s-land. Their dangerous mission had begun.

The German searchlights sprang up to meet them, but the pilot had little difficulty in avoiding them; little dull red, twinkling fireflies in the distance showed where the German archie-gunners were making poor shooting. For a quarter of an hour they flew thus, each busy with his own thoughts, and then Rex throttled back into an easy glide, peering ahead for his landmarks.

It was now quite dark and the earth appeared as a vast black shadow beneath them, a shadow only broken by tiny points of light behind them where bursting shells marked the position of the lines. Almost silently they crept through the night, a sinister shadow in the lonely sky. Tony felt the nose of the machine tip down and swerve slightly and he knew that Rex had spotted the field which they had chosen for their landing-ground. Ahead of them, the landscape was shrouded in darkness, except where, in the far distance, a few twinkling lights began to appear, marking the position of the occupied town of Lille; a tiny, glowing, moving spark showed where a train was feeling its way into the zone of war. Lower and lower they sank, almost at stalling point, and Tony, leaning over the side, began to pick out details in the darkness below. The details became clearer; roads, trees and woods were easily distinguishable.

The machine tilted, and a gust of air striking Tony on the side of the face told him that his pilot was slipping off the last two or three hundred feet of height. The machine swung up on even keel again and seemed to brush the tree-tops.

Rex, every fibre of his body tense, was watching the ground. The joystick came back, back, a fraction more, as he held the machine off. The wheels touched, the tailskid dragged, and, as they ran slowly to a standstill, he switched off the engine and sat perfectly still, listening intently. All was silent as the grave.

Tony felt the same prickly sensation underneath his skin as he had the last time they landed in Germany after dark; with parted lips and straining eyes he stood in his cockpit staring into the gloom around him. “I think this is the most trying part of all,” he said as they climbed quietly from their seats and dragged the machine to the hedge by the side of the field. Flying-coats, helmets and goggles were thrown over the lower plane in readiness for their return; greasy caps replaced the flying-helmets on their heads.

“Come on,” said Rex, starting off at a steady pace along the hedge. “There is only one way to do a job like this if we are to be back before dawn,” he muttered quietly in guttural German as they walked. “We’ve got to behave as if we were afraid of nothing or nobody. If we start dodging about or lying doggo at every sound we shall be here all night, besides attracting attention to ourselves if anybody sees us.”

Climbing a stile they reached the main Lille road and set off in the direction of the town in the slouching gait of the farm labourer.

A car overtook and passed them without even checking its speed. Once or twice they passed small parties of German soldiers, and once an old woman muttered something unintelligible at them as she passed with a heavy shopping basket in her hand. A lorry trundled down the road from behind. As it drew level Rex looked quickly up and down the road. No one was in sight. “Come on,” he said tersely and took a flying leap at the tail board. The lorry rumbled on with the two boys swinging their legs over the back. “I never walk when I can ride,” observed Rex sagely, as they bumped along over the ruts made by heavy transport-wagons and guns.

In less than ten minutes they were on the outskirts of the town and seizing a suitable moment they dropped off and fell in line on the pavement. German troops were everywhere; batteries of guns, ambulances, wagons and other signs of the German occupation were parked in gardens and squares. A number of civilians were about and Rex remarked several military police, but they might have lived in the town all their lives for all the notice that was taken of them.

“This should be it,” said Rex at last, stopping at a narrow side-street off the main square. He glanced up at the name-plate nailed on to the wall of a house opposite him. “Rue de la Concorde,” he said softly. “Here we are.”

It was one of those squalid streets so often found leading into a main thoroughfare. Dirty and rusty signs hung out over the pavement. Most of the shutters were closed, some hanging crazily on their hinges. The street was in darkness except for one or two widely-separated lamp-posts, and as far as they could see deserted. The smell of stale food and unwashed clothes greeted them as they turned into it, their footsteps echoing noisily on the flagstones. A few drops of rain had started to fall and the road shone dismally where the feeble yellow light of the street lamps fell on it.

Rex was counting the numbers on the doors. A sound of rattling crocks and laughter came from somewhere just ahead and Tony nudged Rex as they passed a vile-looking semi-basement bar, packed with German troops to whom a slatternly-looking woman was serving mugs of beer. At the next house beyond it Rex stopped. “This is it,” he said in a low voice. He turned an eye on the villainous-looking grog shop, and grinned. “I wish it was a bit farther away from that,” he muttered as they turned into the doorway. The door was ajar and through the crack they could see a dirty hall, lighted by a single flickering gas-jet with a broken globe. A greasy deal table leaned crookedly against the wall; on it was a small iron bell with a spring attached, the sort one still sometimes sees behind shop doors.

Rex pushed the door open, entered, and without any hesitation picked up the bell and shook it. Tony bit his lip as the harsh jangle echoed noisily along the empty hall. As the echoes died away a door at the end opened and an uncouth figure with long hair and a shade over one eye shambled towards them.

“What brings you here at this hour of night?” it said in a high quavering voice.

“Fritz asked me to leave a message to say he would soon be home,” replied Rex instantly.

“When am I to expect him?” almost snarled the man.

“At ten o’clock.”

Without another word the man opened a door which led into a room off the hall and beckoned them to follow.

They found themselves in a dingy room which was even more depressing than the hall. The man lit an incandescent gas-jet, but the burner was broken and a streak of flame danced crookedly up and down the side, throwing flickering shadows into the corners of the room. The Venetian blind was lowered, but the slats hung at all angles in the last stages of dilapidation; two chairs and an old stained table comprised the entire furniture.

“Well, where is it?” said the man curtly, with such a change of tone that Rex started; he handed him the letter without a word.

Their ill-visaged host tore open the flap impatiently and read in silence. He looked up when he had finished and eyed Rex narrowly with his one good eye. “Wait,” he said folding the letter and placing it in his pocket. He went out and shut the door.

“Lord! I hope he won’t be long,” whispered Tony, “this place gives me the creeps.”

“It isn’t exactly cheerful, I must admit,” answered Rex in a low voice. “I wonder what’s in here,” he added, opening a cupboard which was let into the wall. It was packed with clothes, some civilian, not unlike the ones they wore, but most of them were old German uniforms. “Ugh,” muttered Rex, “I don’t like the look of those.” He crossed over to the window and peered into the street through the slats of the broken blind. The next moment he was back in the room, white-faced and agitated. “Quick!” he gasped. “That man over there—the man under the lamp-post.”

Tony sprang to the window and looked. Standing in the rain under the feeble light of the lamp was a man wearing a long mackintosh. A Hamburg hat was pulled down over his eyes concealing his face, and even as Tony watched he turned his back and walked slowly up the street. “I don’t know who it is,” he said. “He’s gone now—who did you think it was?”

“I thought it was—Fairfax.”

“Fairfax!”

“He looked up as I looked out and the light fell on his face just for an instant. I could have sworn it was Fairfax.”

“It couldn’t be! I think we are getting nervous,” said Tony in a voice that was not quite steady, peering again out of the window. “Look!” he said in a strained voice, “—those two German soldiers over there—what are they doing?”

Before Rex could reply their host had burst into the room. “The house is being surrounded!” he snapped. “It is every man for himself,” and was gone.

The two boys heard the front door slam and a figure darted quickly along the path. Before he had gone five yards two other figures had leapt from the shadow of a doorway and seized him. There was a short sharp struggle and the three disappeared into the darkness.

Rex felt his lips turn oddly dry. “Let’s try the back,” he muttered grimly, “we’ve no time to lose.” The light in the hall had been extinguished, but with the aid of matches they groped their way to the kitchen at the rear. “Too late!” cried Rex in dismay, “we are trapped.” In the small courtyard stood four dark figures; the spiked helmets on their heads left no doubt as to who they were. “Quick!” cried Rex. “The roof—it’s our only chance. No, wait!”

With Tony at his heels he hurried back to the room near the front door, turned down the light to a glimmer, flung open the cupboard and dragged the contents out on to the floor with one sweep of his arm. “Get yourself a uniform,” he hissed in Tony’s ear. It was the work of a moment to rip off their dark coats and trousers and replace them with the German field-grey. Rex turned out the light and groped his way to the door. At the foot of the stairs he paused.

“They must be waiting for us to come out,” he whispered, “but I expect they’ll rush the house at any moment.”

They felt their way up the stairs as fast as they could, their heavy boots making a terrible noise on the uncarpeted boards. Two flights brought them to an attic which was evidently the top of the house, and Rex strode to a small gable window which showed as a small pale square, a shade less dark than their surroundings. He turned the latch and opened it. “It’s as black as pitch outside,” he whispered, “and if we can get out they may not see us.”

As so often happens with the ornately-decorated French houses, even of the poorer class, a cornice ran along the side of the building just below the window. “If it breaks, we’re sunk,” whispered Rex, “but we’re that, anyhow, so we might as well try it,” he muttered as he swung himself out, and with his feet on the narrow ledge and his hands gripping the spouting, he started edging along the side of the wall. Tony followed. They reached another window like the one they had just left. With his heart in his mouth Rex released his hold on the spouting with one hand, groped for the window, inserted his nails at the edge and pulled. It opened easily. “Thank God,” he muttered as he slipped inside.

For a full minute they stood trembling and panting in the darkness as they recovered from their nerve-racking ordeal. “We are in the house on the left,” breathed Rex, “let me see—that’s—good Lord! we are in the house with the bar on the ground floor. Well, it’s our only chance,” he went on after a long pause, “we’ve got to risk it, we can’t go back.”

They crossed the room quietly and opened the door. All was darkness outside. Rex struck a match and they felt their way down a flight of rickety stairs. A gas-jet was burning on the next landing below. As they reached it, a door opened in the corridor and an untidy-looking woman appeared on the threshold.

“What are you doing up there?” she chided them. “You know you’ve no business up there.”

“Sorry,” said Rex, “I was looking——”

But the woman had passed on and entered another room. They descended another flight of stairs and stood before a door through which came the chink of glasses, coarse guttural voices and laughter. Rex looked around in despair; there was no other way out except through the door. “We’ve got to do it,” he muttered hoarsely. “Pretend you’re drunk, watch me and do as I do.” He opened the door, blinked for a moment in the sudden flood of light that met their eyes, and swayed unsteadily into the room. Except for a few jeers directed at them no one appeared to pay much attention as they lurched their way across the sawdust-strewn floor in the direction of the street door. Rex caught a gleam of a bayonet outside and turned back into the room, hiccoughing. “Nothing doing,” he whispered to his companion between the hiccoughs.

An Unter-Offizier, wearing the Iron Cross, was leaning on the bar boasting loudly of the number of Englishmen he had killed. A mug of beer stood near his elbow. Rex thrust his way unceremoniously through the group of listeners, picked up the beer and drank it at a gulp.

“Hi! What are you doing—that’s my beer,” roared the N.C.O. in a fury.

“Your beer, your beer, thash my beer,” hiccoughed Rex stupidly, swaying slightly to and fro with an inane grin on his face. “Geroff, you ugly—hic—hic—schwine.” He made a futile jab at the bristling face before him.

“Yesh, thash his beer,” protested Tony, joining in the argument, “you’re the s-short o’ feller take a sholdier’s beer,” he snorted aggressively. A hush had fallen on the room; the N.C.O. glared at the pair with a baleful gleam in his eyes.

“You’re drunk, you two,” he snarled. “I’ll put you somewhere where you can cool your heels until the morning and then I’ll deal with you.”

He walked to the door and blew a whistle. Two soldiers wearing the black-and-white armlets of the military police came up at the double. “Take those two to the guard-room,” roared the Unter-Offizier. “They’re drunk. Don’t stand any nonsense.”

“Me drunksh!” cried Rex with an incredulous giggle, “you’re drunksh.”

There was a snigger of laughter; out of the corner of his eye Rex saw the two men on guard at the door peering into the room.

“Take ’em away,” roared the irate N.C.O.

Struggling and protesting the two boys were dragged to the door. The two guards on duty grinned as they passed and made no attempt to stop them. Out into the night and down the dripping pavement they were marched, each held by the scruff of the neck with no light grip. They had gone about a hundred yards and had reached a narrow alley when Rex heard a whistle blown in the street behind them. There was a crash of a door being forced open and he knew that the house from which they had escaped was being rushed. He gave a hoarse gurgle, clutched his throat and sagged limply into the arms of the man who held him.

“Here, hold up, you—what’s the matter?” cried the policeman, and then, “Karl, give me a hand, this pig’s fainted.” For a moment he released his hold on his prisoner’s collar, and as he did so Rex stiffened into lightning-like activity. His arm jerked forward with all the strength and weight of his body behind it. His fist took the burly German in the pit of the stomach. The man gave a gasping grunt of agony and fell flat on his face. Whirling like a flash Rex leapt at the second policeman, but Tony had already tackled his man; one arm was round his throat and the other hand was over his mouth. Rex bent down and jerked his legs from under him and he crashed to the pavement. Tony seized the German by the collar, pulled up his head and banged it down on the stone flags with all his force. The struggling body went limp.

There was a shrill whistle and a shout of alarm from higher up the street. “This way!” snapped Rex and together they raced down the alley. It was raining steadily and the water squelched from under their feet as they ran; fortunately not a soul was in sight. The alley grew darker as they left the region of lamp-posts and Rex ran with his eyes straining anxiously ahead. Suddenly he pulled up with a cry of dismay; facing them was a high brick wall. “My God! It’s a cul-de-sac!” he gasped, and at the same instant there was a loud outcry of voices from the corner of the street and the sound of running footsteps. “Here’s a door!” cried Tony breathlessly. He turned the handle and flung himself against it. It was locked. Rex put his shoulder to it but it was of heavy oak and would not budge. The footsteps were close now, and rapidly drawing nearer. “Over the top,” grunted Rex and took a flying leap at the wall. His hands clutched the coping, he pulled himself up, sat astride for a moment to see that Tony had managed it, and then dropped into the inky blackness over the other side. Tony landed with a thud beside him. The darkness was intense; not a spot of light broke it anywhere, as, hand in hand, they groped their way forward over soft patches of earth which clogged their feet and told them that they were in some sort of a garden.

“Where the dickens are we?” gasped Tony, and then staggered back with his hand over his eyes. A flash-lamp had split the darkness like a sword and the light was directed on them.

“I’ve got you at last, you devils, have I?” snarled a malevolent voice. “I’ll teach you to steal my eggs!”

Rex mentally cursed the soldiers who had evidently been robbing the man’s hen-roost. Dimly, behind the light, he could see the bulky form of the man pointing a double-barrel sporting gun at them. Outside, the footsteps were nearly opposite.

“It wasn’t us, it was them!” yelled Rex despairingly, pointing over the man’s shoulder. The trick was as old as the hills, but it worked. With an oath the man swung round, and as he turned Rex sprang at him like a tiger. With a sharp twist he tore the gun from his hands and with his shoulder sent him reeling. The torch flew across the ground and lay pointing in the direction of the wall, from which came hoarse cries and a thunder of rifle-butts hammering on the door. As Rex turned it burst open with a crash. He caught a fleeting glimpse of armed men in the doorway, and throwing the gun to his shoulder blazed both barrels straight at them. Without waiting to see the result he flung the now useless gun away and dashed off at a stumbling run in the opposite direction. “Where are you, Tony?” he gasped.

“I’m with you,” said a voice near at hand, and together they ran blindly on into the darkness which seemed to press on them from all sides. A hedge loomed up before them and without waiting to see what was over the other side they plunged through it, regardless of thorns and brambles. The next instant they were tumbling head over heels down a steep slope, grabbing wildly at the sliding earth for something to check their fall. They landed in a heap at the bottom, gasping, with the wind knocked out of them. The darkness was as the darkness of the Pit.

“Are you hurt, Tony?” cried Rex, struggling painfully to his feet. He caught his toe against a projection and pitched headlong again. Groping on the ground, his hand came in contact with a cold iron rail. “Great heaven!” he said hoarsely, “we’re on the railway line.” A dull rumbling roar, rapidly approaching, filled the air, and the headlights of a locomotive flashed into sight round a bend not a hundred yards away.

They flung themselves down on the bank of the cutting into which they had fallen as the train swept by; through the windows they could see that it was packed with German troops, no doubt being rushed towards the trenches. “This is a bit of luck,” exclaimed Rex as the tail-light of the train swept round the next corner out of sight. “I know where I am now. Come on, this way.”

They walked for some time in silence, often stopping to grope their way in uncertainty; they could no longer hear the sound of the hue and cry behind them and assumed that the pursuers had gone off in another direction. Once the moon showed dimly for a few minutes, and Rex pointed to it with a muttered exclamation of alarm.

“What’s the matter?” asked Tony anxiously.

“I don’t like the look of it,” replied Rex. “Look at that mist. If that fog comes down before we get to the machine there’ll be no finding it, and if we did find it we couldn’t get off the ground. We had better push on as fast as we can go.”

They hurried their pace until Rex, who was leading, turned, and laid a restraining hand on Tony’s arm.

“Here’s the bridge,” he said quietly, “just in front of us. This is where the railway goes under the bridge we crossed as we went into the town. We were lucky to strike this line and no mistake; keep your eyes skinned in case anybody is about.”

Their fears proved groundless and reaching the road they broke into a steady dog-trot. “This stuff is getting worse,” panted Rex once between breaths as they ran, “we’ve no time to lose. If it gets any worse we’re sunk. This way—this is where we turn off.”

At the stile which they had crossed on their outward journey Rex stopped for a few moments to listen, but only the dripping of the moisture off the trees around them broke the silence. They started off again at a quick run down the side of the hedge by which they had left the Bristol, but fifty yards away from it, however, they slackened their speed and approached warily. “It’s all right, she’s here, and I can’t see anybody about,” whispered Rex. “—Oh, good Lor’, that’s done it!”

His exclamation of disgust was echoed by Tony and not without cause. The threatening fog had come down on them like a blanket, effectively blotting out everything in an impenetrable shroud of opaque moisture. Even at a distance of a yard they were unable to see each other. “Catch hold of my coat and don’t let go,” said Rex desperately. “If we ever get parted in this stuff we’ll never find each other again.”

Only those who have been caught in the open in a fog at night know the feeling of utter blind helplessness which it produces. All sense of space and direction disappears, leaving one with the impression that every step will involve collision with an invisible obstruction.

Fortunately Rex had the hedge beside him to give him his direction, and with his right hand brushing the bushes and his left hand held out before him, he groped his way, inch by inch, towards the machine. His hand encountered something solid and he felt it gingerly. Presently he made it out to be the leading edge of a lower wing. “Here it is,” he said shortly, but even then they were unable to see the machine. “This fog is something I didn’t bargain for,” he added savagely.

“What can we do?” asked Tony in a low voice.

“Nothing. Absolutely nothing, except wait,” replied Rex feeling his way to an undercarriage wheel and squatting on it. “An aeroplane can do a lot of things with a man, and a man can do a lot of things with an aeroplane, but there is one thing he can’t do with it, and that is get it off the ground in a fog like this.”

“There is a straight run ahead of the machine, we know that much,” returned Tony helpfully.

“So there may be; don’t you try and teach me my job,” answered Rex. “Even if there is, how the devil do you think I can hold a machine straight when I can’t see a yard in front of me? Even suppose I did get off, what then? How thick is this stuff? We don’t know. It might only be a hundred feet, but on the other hand it might be five thousand, and the pilot hasn’t been born yet who could keep a machine on even keel in this soup for more than three minutes. Even if I did get through it, I could never get down again, that is, assuming that this blanket stretches over France, as I expect it does. Our chances of getting down without hitting anything would be about ten million to one. No! We stay where we are; there are no two ways about that.”

An hour passed slowly and still the weather remained unchanged. Another hour ticked by in silence except for the dreary drip, drip, drip of water trickling off the wings.

“How long have we been here?” asked Tony at last, and the sound of his voice made Rex jump.

“About seven years, I think,” answered Rex gloomily, “but it seems like ten.”

“Only seven years—it seemed like eternity to me,” moaned Tony in a hollow voice.

The minutes dragged by on leaden wings, and Tony, who had seated himself on the other wheel, rested his chin on his hand despondently. “I can’t stand much more of this,” he said finally in a strained voice, “I shall go crazy if something doesn’t happen soon; I’ve never been so cold in my life. For goodness’ sake talk about something or I shall scream.”

“Something is happening,” replied Rex soberly, “it is just beginning to get light, but the fog hasn’t lifted.”

In another quarter of an hour they could see each other faintly through a clammy belt of moisture. Rex looked at his watch. “It’s nearly half-past six,” he muttered, half to himself. “If we don’t get a breeze within the next half-hour to blow this stuff away it might hang about for hours, and sooner or later somebody’s bound to come along here.”

Another hour passed slowly and at the end of it Rex arose and shook himself. “Get aboard,” he said tersely, “I’ve finished waiting.”

“What are the chances?” asked Tony quietly.

“Not very bright,” admitted the pilot. “Visibility is about ten yards, but we’ve one thing in our favour, and that is, the knowledge of a clear run ahead. I might get off, and by holding her down and zooming, go right through it”—he indicated the fog with his thumb. “If it’s very thick——” he shrugged his shoulders “—well, it’ll be just too bad, that’s all. If we do get off, I’m going to fly south-west and keep on flying till we come to the end of it. If there is no break I shall just fly until the petrol gives out, and that will mean pancaking to say the best of it. If I do, don’t jump. Strap yourself in, cock your knees up to your chin, cover your face and hope for the best. One thing is certain, we daren’t stay here any longer. Go ahead, laddie, swing her,” he finished laconically with a nod towards the prop. He climbed into his seat. “Switches off!” he sang out.

Tony turned the prop. round once or twice and balanced it on the point of contact. “Contact!” he called.

Rex flipped his switch on. Tony put his weight behind the swing and the engine burst into its steady purr, ticking over with the regularity of a sewing machine as Rex throttled back to wait for it to warm up.

“I shall have to let her get thoroughly warm,” he said as Tony climbed into his seat. “I daren’t risk choking her.”

For ten minutes they waited while Rex watched the thermometer climb slowly to the safety line. He was about to signal to Tony that he was going to take off when something made him look up. Down the side of the hedge, not thirty feet away, rode a troop of Uhlans with an officer at their head. There was a shout from the leader as he saw that he was perceived, but Tony’s gasp of horror was drowned in the mighty bellow of the 275 horse-power Rolls-Royce Eagle engine as Rex jammed open the throttle and started off across the field, gaining speed at every second. The crack of carbines came faintly to his ears, but it was not bullets that he feared, for he knew the Uhlans were shooting blindly into the fog; it was what lay before him that made him wince.

The next sixty seconds seemed like a long drawn-out nightmare. Tail up they roared across the sodden turf into a solid bank of opaque white vapour. Would she never lift? Ah, the wheels were only just touching now; a final bump and she was off. Rex held the stick forward as long as he dared, and then, as something grey loomed up in front of him, he pulled the stick nearly back into his stomach. The seconds ticked slowly by as they zoomed into the enshrouding vapour. Rex, tight-lipped, began to ease the stick forward as the needle of the air speed indicator started to waver and then droop. But it was getting lighter now. The mist was lighter and whiter, and then, with a suddenness that was startling, they burst out into blazing sunshine.

Rex blinked like an owl in the light after the sombre darkness below; the glare was dazzling, but he looked round at his observer with a triumphant upward swing of his thumb. As he turned south-west by his compass he looked anxiously around the sky, searching every quarter slowly and methodically, but he could see no other machines; they were alone in the sky.

Below them a plain of snowy whiteness stretched, it seemed, to infinity; above them a sky of purest cobalt blue merged slowly into turquoise as it curved over and kissed the mist at the distant horizon. Not a speck broke the perfect harmony of blue and white as they skimmed along above the cloud tops in a silent world of their own. It was hard to believe that less than two thousand feet below, not a mile away, half a million men were entrenched in a gloomy land of mud and murk, grappling at each other’s throats in the greatest struggle the world had ever known.

For nearly half an hour they flew thus, Rex watching his compass, Tony maintaining a vigilant watch around. Suddenly the engine spluttered, but picked up again as the pilot switched over from the main tank to the gravity tank. “I’ve about twenty minutes’ petrol left, but we must be over our own side of the lines by now,” he shouted over his shoulder in answer to Tony’s look of enquiry. Another fifteen minutes passed; Rex throttled back and dropped slowly into the mist, eyes strained downwards. His altimeter began to swing back; at five hundred feet they were still enveloped in the grey opaque vapour. At two hundred feet they emerged from below the cloud-bank into fairly clear atmosphere; the mist was slowly rising, and woods and fields lay below. Rex made no attempt to find out where they were, but concentrated on getting down immediately into the largest field available. He chose an old stubble field and landed in the middle of it without any great difficulty. He stood up in his cockpit and looked around; some Tommies were staring at them over a hedge not far away. “Well, we are at least over our own side again, thank goodness,” he said, as he sat down again with a tired sigh. “How long is it since we took off—it seems weeks to me? Well, we had better find out where we are and get some petrol; keep your coat buttoned up—if anybody catches sight of these uniforms we are wearing we might stop a bullet yet, and that would be a tragedy after getting out of the hole we were in last night.”

It was past noon when they finally reached home and they lost no time in getting to their quarters and stripping off the hated uniforms, which they stowed away out of sight. A meal and a bath and they flung themselves down in Rex’s room to rest. No sooner had they done so than Jimmy Brown, the Recording Officer, entered.

“I’ve just heard you were home,” he said. “I had just about given you up. Major Trevor has been on the ’phone once or twice and on the last occasion he told me he was afraid you had gone West and that you had better be reported ‘missing.’ ”

“I think we had better go and see him,” replied Rex rising. “Come on, Tony, we can sleep afterwards.”

They found Major Trevor in his office and he gazed at them for some moments speechlessly when they entered the room. “I can’t tell you how glad and relieved I am to see you back,” he said. “It is a weight off my mind. I had quite given you up for lost. Frankly, I never expected to see you again and have been reproaching myself ever since you went for letting you go. Well, how did you get on?”

Briefly Rex recounted their adventures, the Major watching him all the while with wide-eyed amazement as the story unfolded.

“You have been lucky; very lucky indeed,” he said soberly at the end. “It is a pity that you couldn’t get the return message, but that could not be helped. You certainly did all in your power and you did remarkably well to bring yourselves back. You must both be very tired; get off to bed now and go on with your other work as soon as you feel fit again.”

A week passed quickly with Rex and Tony pursuing their quest with redoubled energy. Major Trevor’s convictions regarding Captain Fairfax had left them seriously disturbed in mind, particularly in view of the fact that they suspected him of being concerned with the betrayal of the rendezvous in Lille; but after the way in which the Major had pooh-poohed the idea of Fairfax being concerned with espionage when they had broached the subject on the occasion of the guest-night, Rex had not mentioned his suspicions when recounting the story of their latest adventure. Had he been quite certain that the man whom he had seen under the lamp was Fairfax, he felt that he might have been justified in re-opening the matter, and while in his heart he felt sure that he had not been mistaken, the one brief glimpse he had had in the darkened street was hardly sufficient proof to warrant it. Yet the failure of their mission and the appearance of the man bearing so striking a resemblance to Fairfax at the crucial moment could hardly be coincidence, he reasoned, particularly as no thought of Fairfax was in his mind when he had looked out of the window of the ill-fated house in Lille and seen the man under the lamp-post.

Against that was the Major’s defence of the man, backed by his undeniably fine record. As Rex put it to Tony, it was impossible to imagine an officer with Fairfax’s record to be in the pay of the enemy, yet it was almost equally impossible to think that they could both have made such an amazing mistake, or that there could be two men so much alike.

Meanwhile, Fairfax had apparently returned to Headquarters after the guest-night and they had not seen the S.E.5 since. Rex, becoming desperate, had resolved upon taking another extremely hazardous chance.

“I have got a feeling in my bones,” he had told Tony the previous evening, “that the centre of this thing is at the Boche aerodrome at Varne, where we saw Fairfax—if it was Fairfax. The only thing I have got to bear that out is the fact that either Fairfax or someone very much like him was there. If it wasn’t Fairfax, well, we’re on a wild-goose chase and we are risking our necks for nothing, but, Trevor or no Trevor, I can’t get it out of my head that Varne is the place to watch. It’s just a hunch, but I am playing it up till we find something or face a firing party. I am going to land again to-morrow at Varne.”

And so it came about that the following morning found them in the Hannoverana again clad in the German pilots’ uniforms, planing down on to the German aerodrome. Rex had thought his plans out very carefully and acted accordingly. Landing some distance from the tarmac he climbed swiftly from the cockpit and bent over a tyre as if examining it. What he actually did was to take a penknife from his pocket and thrust it with a vicious jab straight into the inner tube. There was a faint hiss of escaping air, and for the benefit of possible watchers he made a gesture of annoyance. Climbing back into his seat he taxied slowly to where several officers and a group of mechanics were standing in front of a hangar. He waved a greeting to von Henkel, the officer who had given him the beer on the previous occasion, and again dismounted, beckoning to the mechanics as he did so.

“Can you fit me a new wheel, or mend that puncture?” he asked the N.C.O. in charge, in fluent German.

“Jawohl, Leutnant,” replied the Unter-Offizier, saluting, and Rex paid no further attention to him, but strolled across to the mildly-interested officers who were now making their way towards the mess. He greeted von Henkel warmly.

“You are the very man I have come to see,” he said. “Did I leave my cigarette-case here the other day? I couldn’t find it anywhere when I got back, so I have slipped over to see if it is here; punctured my confounded wheel landing, too,” he added ruefully.

“No, I haven’t seen a strange case about,” replied the German, “but come in and have a beer while I ask the mess waiters if they have seen one.”

Enquiries naturally proving fruitless they returned to the front of the mess, and stood talking until the departure of a big formation left them almost alone.

“Well, Koepler, let’s stroll along and see how they are getting on with that wheel,” said Rex loudly to Tony for the benefit of anyone within earshot, and together they meandered unconcernedly towards the sheds. The tyre was still in process of being repaired and they walked up and down, apparently aimlessly, in bored impatience. Actually they were subjecting everything within sight to a searching scrutiny. The door of every hangar except one stood wide open, and it was only the work of a few minutes to ascertain that they housed nothing resembling an S.E.5.

“I’m going to see what’s in that end shed,” said Rex quietly at the end of one of their perambulations. “Let’s go round the back, no one is paying the slightest attention to us.”

Casually, with their hands thrust deep in their pockets, and pausing every few steps to talk, they slowly made their way to the rear of the hangars and then strolled along until they were behind the one with closed doors. As they expected there were one or two small windows quite low down at the back. “Go straight on, Tony, I’ll look,” said Rex softly. Tony heard a quick intake of breath, but did not turn, and the next instant Rex had rejoined him, linked his arm through his own, and was continuing the walk as if nothing had happened. “Let’s sit down,” he said loudly, pointing to an empty oil drum.

“Well, what was it?” whispered Tony under his breath.

Rex looked around keenly before replying. “There is a Bristol fighter and a D.H.4 in there, both looking as if they are being used,” said Rex quietly.

The sound of an aero engine over their heads made them look up, and in spite of himself Tony clutched Rex by the arm. An S.E.5 was just swinging in to land.

“Sit quite still,” said Rex evenly, “this is where we learn something. If it’s Fairfax and he spots us, we are in for trouble, but I hope he won’t see us. If it isn’t him it doesn’t matter, but I shall be very interested indeed to see the face of the man who is flying that machine.”

Out of the corner of his eye Rex watched the S.E. land and taxi tail up towards the shed beside which they were sitting. A mechanic, who seemed to know exactly what to do, swung back the door, and the machine taxied straight in without stopping. The door swung to behind it and the mechanic returned to the group working on the Hannoverana.

“This is where we click,” said Rex, rising to his feet. “I must see who is inside that hangar.”

Three paces brought them to the window and they peeped in; the S.E.5 was there, but the cockpit was empty and the pilot nowhere in sight. “Stand still,” said Rex, and, bending low, hurried to the next window and peeped up over the sill. He was back in a second, his face a trifle pale.

“It’s Fairfax,” he said briefly. “We had better stand here until he goes down to the mess, and then we’ll push off immediately the wheel is finished. Hullo, they’ve finished it now, they are going away.”

“Let us get off while we have the chance,” muttered Tony.

“Wait,” replied Rex grimly. “Listen, Tony. I saw Fairfax take a bundle of papers—they looked like plans or maps—from his pocket. He is in a cubicle, changing, and I saw him put the papers on a table beside him. They might be something of vital importance to our people, and I am going in to get them.”

“Good God, Rex, are you mad!” gasped Tony.

“We’ve got to do it,” retorted Rex doggedly. “A bold stroke is our best chance.”

They walked openly to the front of the hangar, opened the door and entered. Rex, with his hand in the pocket of his flying-coat, walked straight to a small door in the side of the hangar, turned the handle and pushed. It was locked on the inside.

“Who is there?” called a voice from within.

“It is me, Hauptmann von Rasberg,” replied Rex harshly.

There was the sound of a key being turned and the door was flung open.

“Stick ’em up, Fairfax,” said Rex crisply in English. “Make a sound and it will be your last.”

The S.E.5 pilot stared as if fascinated at the muzzle of Rex’s Smith and Wesson revolver. Tony closed the door. “Bah!” sneered Fairfax. “One shout and I could have a dozen men here.”

“You’re right,” agreed Rex grimly, “but you wouldn’t see ’em. Try it, and I’ll blow you in half, and I mean that, you dirty spy. I don’t know why I don’t shoot you, anyhow. These are what I came for,” he said, reaching out, and picking up the packet of papers tied with red tape which were lying on the table, he dropped them with a quick movement into the pocket of his flying-coat. “If you’re wise you’ll stand still,” he snarled as Fairfax made an involuntary movement. “Stay where you are. If I have to shoot, remember it will be you that stops the first bullet.” He took the key out of the keyhole on the inside of the door, went out, and then locked the door swiftly on the outside. It was the work of a moment. With Tony at his heels he hurried towards the hangar door, but before they could reach it Fairfax was kicking and hammering on the door of his cubicle. As they walked across the tarmac several mechanics passed them, hurrying towards the hangar. “They think he is shouting for them,” said Rex quietly as the muffled sound of Fairfax’s voice reached their ears. “Swing the prop. and look lively—no, stand back, here’s a mechanic coming to do it, get into your seat.”

For ten seconds that seemed like eternity to Tony the mechanic slowly pulled round the big propeller. He paused when it was balanced on contact.

“Contact!” called Rex.

The mechanic swung the prop., but the only sound that came from the engine was a faint hiss as the cylinders failed to fire. A low groan of despair broke from Tony’s lips.

“Try her again!” cried Rex coolly, and the mechanic once more stepped forward and swung the propeller. The engine started with a roar. Out of the corner of his eye Rex saw the hangar door flung open and Fairfax race towards them, but he pushed the throttle open, and, narrowly missing the mechanic, raced across the aerodrome. There had been no time to turn round facing the wind, and he knew he was taking off down-wind. The trees on the far side of the aerodrome seemed to rush towards him and he bit his lip. Could he clear them? The machine lifted at last, and, as Rex pulled the stick back, he saw the tree-tops sway beneath them as the undercarriage almost brushed them. He glanced over his shoulder. Tony’s face was buried in his hands. “Closish!” he bawled.

Tony leaned over and put his mouth against Rex’s ear. “You’ll kill us both doing that one of these days!” he yelled.

Rex nodded. “Probably!” he bellowed, above the noise of the engine. He made a wide climbing turn and pointed down as he did so. On the ground in front of the hangar stood Fairfax and a group of mechanics, staring upwards. He waved mockingly in farewell and then headed for the lines, climbing steeply. “I’m going to climb to eighteen thousand and glide over!” he yelled to Tony. “I don’t want to run into archie or any of our scout patrols near the ground!” and Tony nodded understandingly.

Even so, they had to turn back twice into the German lines to avoid patrols of British scouts, and it took them nearly an hour to reach Neuville. They glided down to a smooth landing and taxied straight up to the hangar door.

“Well, that’s that,” said Rex quietly as he took off his flying-kit and flung it over the lower plane. “Let’s go and change. The cat’s out of the bag now and no mistake. Let’s go along and see the Major. I felt it in my bones that we were on the track with that S.E.5,” he declared as they made their way towards the Major’s office. “I thought we both couldn’t be mistaken about Fairfax. Great scott! Just imagine it, a spy in Divisional H.Q.—but there, it’s happened often enough in history,” he observed sagely. “Someone is going to get his nose twisted over this business if I know anything. It’ll shake the Major up, too, when we tell him.”

They returned the salute of the orderly on duty at the outer door and hurried to the Major’s room. Rex knocked sharply.

“Come in,” called a voice cheerfully. Rex pushed the door right open and they made as if to enter. Instead, they stopped dead, and stood rooted to the ground, staring in utter dumb amazement. In the armchair, with a book on his lap and his feet resting comfortably on the Major’s desk, sat an officer. It was Captain Fairfax.

“Hullo! It’s you, Lovell—and you, Fraser,” he called cheerfully. “Where have you sprung from? What’s the matter with you?” he went on, “what are you staring at? You look as if you had seen a ghost.”

Rex took a slow pace forward into the room. For a second or two he struggled with himself, unable to speak, so great had been the shock. “And where the devil have you sprung from?” he said at last in a strained voice. “How long have you been here?”

“Oh, about half an hour, I suppose,” replied Fairfax easily. “I’ve just brought orders over from H.Q., but I wanted a word with the Major, and as he was out I decided to wait until he came back. I had to get his signature for orders, anyway,” he added casually, rising and yawning. “I wish he’d get a move on. I shall be late for dinner. Have a cigarette?” he said, holding out his case. “What’s the matter with you?” he said again, eyeing Rex curiously after a moment’s pause. “Have I got smallpox or something?”

“Oh, no, it’s nothing,” replied Rex stonily. “I expected to find the Major here, that’s all.”

“Well, don’t look so peeved about it, he’ll be here in a minute,” replied Fairfax evenly. “Ah, here he is now. Hullo, Major!”

The Major looked around in surprise as he entered. “Quite a party, eh?” he chuckled. “Well, Fairfax, what brought you over—do you want to see the General?”

“No, I’ve just brought the doings over, here they are—sign on the dotted line, please—thanks.”

Fairfax put the orders in his pocket and moved towards the door.

“Where are you going?” asked Rex coolly.

“Back to H.Q., of course. Why?”

“Oh, nothing. I just wondered if we should see you over at our place to-night, we’ve got a guest-night on, that’s all.”

“Sorry, I can’t manage to-night. See you another time. Good-bye, sir. Good-bye, chaps,” called Fairfax as he closed the door behind him.

“Pardon me, sir——” began Rex.

“Just a minute while I sign these documents,” broke in the Major. “My orderly is waiting for them.”

“Now,” he said, five minutes later, as he flung his pen on the desk, “what——”

But Rex wasn’t listening. He was staring at an S.E.5 which had taxied out and turned into the wind at the lower end of the aerodrome. Even as he watched, the engine roared, the tail lifted, and the machine rose gracefully into the air.

“Where did I leave my flying-coat, Tony?” asked Rex with a start.

“Down in the hangar on the Bristol,” replied Tony.

With a brisk, “Pardon me, sir,” Rex, with Tony at his heels, was sprinting for dear life down the line of hangars. They burst into the one in which they had left the Bristol and hurried towards the machine. Their flying-kit was exactly as they had left it. Rex snatched up his flying-coat and thrust his hand into the pocket; a cry of dismay broke from his lips. “They’re gone!” he muttered through his clenched teeth.

“You mean the plans——?”

“What else, idiot!” snarled Rex. “Sorry, old boy, I didn’t mean that,” he went on quickly, “but I’m a bit upset. We took a pretty big risk to get those papers, which, incidentally, were our only hope of proving anything against Fairfax, and now he’s got ’em back again. It’s no earthly use going after him in the Bristol; he’s halfway home already.” He paused and scratched his head reflectively. “The fact is, Tony,” he went on slowly, “this business is getting a bit beyond us. I can’t stand many more of these shocks. When I saw Fairfax sitting in that chair I nearly dropped dead, and that’s a fact.”

“So did I,” admitted Tony ruefully. “I’m beginning to think he’s got a double.”

“He’s got something,” said Rex bitterly. “A man can’t be in two places at once, and if that wasn’t Fairfax at Varne then I’ll eat my hat. Yet when we get here he’s here. Wait a minute, though, he might have done it. Yes, he might have raced straight back near the ground in the S.E. while we were climbing for height, and then we had to waste time because of those S.E.5’s and Camels. That was it. He dashed straight off behind us with the object of getting here first and getting the papers back. What a nerve the fellow must have. Let’s see, he said he was going back to H.Q., didn’t he? We’ll soon prove the truth of that. He’s in that S.E.5, I should say.”

“How are you going to find out?” exclaimed Tony.

“If he went back to Headquarters as he said, he should be there by now. Let’s go and ring him up,” replied Rex.

“Here, what are you boys up to?” said the Major irritably as they entered. “I can’t have you dashing in and out of my office like this.”

“May I use your ’phone, sir?” asked Rex civilly.

“Certainly.”

Rex put the call through to Divisional Headquarters. “I want Captain Fairfax’s office, please,” he said curtly to the orderly who answered him.

“Here you are, sir,” said the telephone orderly.

“Hullo, yes?” called a voice.

“Is that Captain Fairfax’s office?” asked Rex.

“Yes, it is.”

“Is Captain Fairfax there?”

“Yes, he is. Do you wish to speak to him?”

“Did you say he was there?” exclaimed Rex incredulously.

“Yes, I said he was—he is here now, do you want to speak to him or do you not?”

“No, it doesn’t matter, thanks,” replied Rex after a moment’s pause, slowly hanging up the receiver. He turned to see Major Trevor looking at him with an expression of marked disapproval.

“What are you worrying Captain Fairfax about?” said the Major shortly. “Have you still got that bee in your bonnet? Didn’t I tell you the other night——”

“Yes, I know, sir,” broke in Rex, “but believe me, I had a reason for ringing up, a good reason. I just had an idea I wanted to verify and this confirms it. Thanks very much. Good night, sir.”

He moved towards the door.

“Have you anything to report?”

Rex shook his head. “No, sir. I may have struck the trail or I may not,” he said slowly. “At present it is a bit difficult to follow, but if it leads to anything I’ll let you know,” he added, as he left the room.

“This is getting worse and worse,” muttered Rex mournfully when they reached home. “There is more in this espionage business than meets the eye. You heard me on the ’phone? You know as well as I do that unless we’re crazy and rushing about on a fool’s errand, Fairfax ought to have been in that S.E.5. We saw him set off by car for Headquarters. He couldn’t have come back and flown there in the S.E.5, because there’s no landing-ground there, and, anyway, they want those papers he’s got in Germany, not at Divisional Headquarters. I am as sure as I am sitting here that that S.E.5 went straight off to Varne and those papers are now in the hands of the German intelligence people. Of course there is always the possibility that he did go back to H.Q. and handed the papers over to someone else, one of his assistants, with instructions to take them back to Varne; yet somehow that doesn’t strike me as likely. I’ll tell you straight, Tony, that when that fellow at the other end of the ’phone told me that Fairfax was actually there—and he said it in the most matter-of-fact way—it completely upset all my calculations. I had made up my mind that he was going to say, ‘No, I’m sorry, he isn’t back yet.’ Well, that’s how it stands, and I am beginning to get a feeling that we are just on the fringe of something pretty deep.”

Tony nodded. “It’s getting a bit too much for me,” he said anxiously, “and, like you, I’ve got the feeling that we are on the track of something. This spying is a cunning game, you’ve got to be cunning or you don’t last long. It is a one-man game, one man playing a lone hand against the rest of the world. You can believe nobody and trust nobody; it doesn’t do to talk when your life is going to pay for the first slip. Well, we’ve learned this much to-day, anyway; we know they’ve got a D.H.4 and a Bristol fighter at Varne, and your hunch was dead right when you said that Varne was the place where this thing starts from. What we’ve got to do is to find the connecting link over this side. That Bristol and the D.H. are used by the Germans to land over this side of the line, and often, too, you may depend on that. If we can find one of them over here, on the ground, or the S.E.5 for that matter, and watch the people that fly them, we shall know a lot more.”

“You’re right,” agreed Rex, “it’s the only thing we can do, but if all we discover is that they are flown by Fairfax, it is going to be a tricky business. He is as slippery as an eel, that chap. How are we going to identify the D.H. or the Bristol if we do see them over this side of the lines, that’s what I want to know.”

“Let us go back and get the numbers of the machines; what fools we were not to do that while we were there,” cried Tony.

“Go back! Are you mad? We can never land at Varne again. We should be arrested and shot before our tailskid was on the ground. Do you suppose that Fairfax, or whoever the chap is, hasn’t told them all about us by now? Of course he has. I’m beginning to think that the hold-up was a mistake. Fairfax knows now we’ve spotted him, and every Boche aerodrome between Belgium and Switzerland is buzzing like a beehive. No, we’ve blotted our copybooks for landing in Germany.”

“Good Lor’, of course we have,” agreed Tony gloomily. “To tell you the truth, I’d forgotten that.”

“Knowing the numbers of the machines wouldn’t help us much now, I’m afraid,” said Rex bitterly. “Fairfax knows that we’ve got his S.E.5 spotted, and that we saw the other two machines over at Varne. Obviously the first thing he would do would be to alter their appearance, particularly the numbers. It’s going to be harder than ever now they know we have seen those kites.”

“Well, those machines are our only chance, we’ve got to be able to identify them or we are absolutely unstuck.”

“What do you suggest doing—going over and painting the wings red or something?”

Tony shook his head. “There’s an easier way than that,” he answered.

“How?”

“Wait a minute—let me see; there are three S.E.5 squadrons, two Bristols, and two D.H.4 squadrons along this section of line, and that covers a good many miles. This is the area over which the enemy are working; I don’t think they are operating any farther afield than this sector. Very well! If every one of our machines had a distinguishing mark on it, such as a black stripe across the top of the centre section and across the fuselage behind the ring markings, we should know very well that any machine not wearing that stripe was up to no good. It wouldn’t be very much trouble for squadrons to put that mark on; it wouldn’t take more than a quarter of an hour to do the whole job. Trevor could easily get it put in Orders that no machine was to leave the ground to-morrow morning until that stripe was put on,” concluded Tony emphatically.

“There are times when you are positively brilliant,” declared Rex, “and this is one of them. We’ll go and see the Major about it right away and ask him to get it put in to-night’s Orders. If that fails we’ve only one card left.”

“What’s that?”

“We shall have to go over the other side again and take another look round Varne aerodrome. We couldn’t do it openly, of course, it would have to be done at night, although I have an idea that those British machines are only used in the daytime when there is something of a very urgent nature to be done. There wouldn’t be much point in using them at night; they could use their own machines then. I don’t quite know what we could do, but it isn’t much use sitting over here waiting for them.”

“Dare we risk landing over there?”

“It’ll be no worse than the night trips we’ve done before. We have gone too far now to hope to get away with it if we are caught. If our identification scheme fails we shall have to go over there and have another prowl round,” said Rex vigorously, rising to his feet and picking up his cap. “Come on, let’s go and get this ‘black stripe’ scheme fixed up with the Major.”

Rex leaned over the rail of the mess veranda and eyed the clear, starlight night moodily. “It annoys me,” he said in an undertone to Tony, “to think that we know so much and get so little. Even now there might be something going on over at Varne that would give us a clue to the whole thing.”

It was the night following the inauguration of their “black stripe” scheme. In order to have the scheme carried out they had found it necessary to tell Major Trevor of their discovery of the British machines in the German hangar, and after he had got over his surprise, he not only agreed to their scheme, but complimented them on it, and took steps for the immediate promulgation of the order by which all Bristol fighters, D.H.4’s and S.E.5’s in that sector of the front were required to wear the identification mark.

Dawn the following morning had found Rex and Tony eagerly pursuing their quest among the clouds, and although they encountered several lone machines of the types they sought, the black stripes were always well in evidence. Naturally one had also been painted on their own Bristol fighter, and Tony could not restrain a smile when, on passing another Bristol fighter, the observer had pointed to his own stripe with a grin and raised his thumbs high in the air. Tony smiled back and wondered what the fellow would have thought had he known the real reason of what must have sounded a strange order, and a ridiculous fad on the part of the authorities.

They had been involved in two combats, and in one of them Rex had shot down an Albatros, but without the usual feeling of satisfaction that follows a victory, and after three patrols of over two hours each they had returned home at dusk weary and dispirited with the failure of their quest.

“Why not drop a 230-lb. bomb on that end hangar right now,” exclaimed Tony in a flash of inspiration.

“And wipe out the only clue we have,” sneered Rex sarcastically, “a fat lot of good that would do. They’d soon get some more machines and then we should be worse off than ever. No, that won’t do. Our only chance of breaking up this scheme lies in catching those machines red-handed. We shall soon have to be doing something about it, though; I have a feeling that Trevor is not too pleased with us, he is beginning to look at us as if we were wasting our time, and his.”

“Well, what else do you suggest?” asked Tony shrugging his shoulders.

“As far as I can see, there is only one thing we can do,” replied Rex, “and that is to go over and have a prowl around the Boche aerodrome at Varne and try to learn something there.”

“What—now?”

“Well, I didn’t necessarily mean now, but it might as well be now as to-morrow,” answered Rex. “We can’t go openly, of course. We should have to land in a field somewhere within walking distance of the aerodrome and then hang about hoping for something to turn up. We might as well take the Hannoverana and wear the uniforms. They know us on the aerodrome, so the result would be the same whatever we were wearing, but if we happened to run into anybody outside the aerodrome the uniforms might enable us to pass unsuspected. It wouldn’t matter much if we were seen except by the officers at Varne and the mechanics who saw us the day we held up Fairfax over there. Even the mechanics would think twice before they laid hands on two officers.”

“Come on, then,” replied Tony impatiently. “I agree with you, we shan’t learn much standing here.”

“All right, give me five minutes to look up a landing-field in the map-room,” answered Rex, “and we’ll get off right away.”

The night was still young when they took off on their nocturnal voyage of exploration. Following their method of the previous occasion they climbed very high and then glided quietly over the German lines in the direction of their objective. Rex picked out his field, dropped down in a wide spiral and made a faultless landing. As the machine ran to a standstill near the edge of the field there was a guttural chorus of surprise and several figures hurried towards them. Rex saw the figures too late, for he was far too close to the hedge to attempt to take off again. He leaned back in his cockpit and beckoned to Tony. “We’ve bought it this time,” he said softly, “but don’t lose your head; leave this to me.” He turned and leaning far out of his cockpit, “Hi! you there,” he shouted, “come and give me a hand with this machine.”

He was standing by the engine swearing fluently in German when the troops, as they turned out to be, arrived. “Who are you?” he said briskly, taking the bull by the horns.

“119th Field Anti-Aircraft Section, Herr Leutnant,” came the reply, and an N.C.O. detached himself from the party.

“Two cylinders are giving us trouble—dirty plugs, I expect,” stated Rex tersely. “I shall have to walk over to Varne and get some tools, that’s our nearest aerodrome,” he went on. “Keep an eye on this machine and don’t let anybody touch it,” he cautioned them sternly.

“Jawohl, Leutnant,” replied the man with a smart salute. “Our gun is over there in the corner and I can easily leave a guard with the machine.”

“Good.” Rex marched off, closely followed by Tony, without another word to the German.

“Good job we were in the Hannoverana and not in the Bristol,” he observed coolly as they strolled along. “They’ll guard that machine with their lives, if I know anything about German discipline. It is surprising what the sight of an officer’s uniform does with them. But go steady now, we aren’t far away; I don’t want to barge into Fairfax or von Henkel. We’ll work our way round the back first and see what is happening in that end hangar. After that we’ll have a squint at the mess through the window.”

Quickly but cautiously they made their way to the hangar that concealed the British machines. A yellow light streamed feebly through the window. Crouching low they crept stealthily along until they were under it and then slowly raised themselves until they could peer over the sill. Their eyes fell on a little group of four or five mechanics in greasy overalls lounging near the D.H.4 in the light of a solitary electric bulb. Vaguely they could see the dim outline of the Bristol fighter beyond it, but it was not that which caused Rex to catch his breath with a sudden hiss. “Look!” he whispered hoarsely. “The black stripe, no wonder we couldn’t find any of their machines to-day.”

Tony’s grip on Rex’s arm instinctively tightened as he saw that his pilot was right. Down the side of the fuselage, behind the ring markings, was the stripe. He turned his eyes upwards and could just see the end of the stripe over the leading edge of the centre section of the top plane.

Before he had time to speak the door at the far end of the hangar was flung open, and von Henkel, followed by an Unter-Offizier, entered. The mechanics sprang to their feet and stood to attention.

“Stand easy,” said the Leutnant with a wave of his cane, “I shall not fly to-night, so you can dismiss. Do not leave camp, though, in case I need you,” and turning on his heel again disappeared into the darkness.

Tony felt Rex nudge him gently in the ribs. The mechanics began packing up their things, one a tool-bag, another an oil-can, and so on. “Let us see where von Henkel goes,” whispered Rex, and started sidling along the hangar. He had almost reached the tarmac when a dog rushed out of the darkness at him, barking furiously. There was a quick cessation of sound inside the hangar, and Rex, knowing that the men had heard the alarm, realised instantly that any further attempt at concealment was out of the question. He strode boldly into the light at the hangar door, praying that none of the mechanics had seen him before or remembered him in connection with the Fairfax affair.

“Down—down!” he shouted at the still barking dog, aiming a vicious blow at its ribs with his foot in typical German fashion as he entered the hangar. “Which of you men painted these marks on Leutnant von Henkel’s machine?” he asked tersely, indicating the black stripe with his finger.

“I did, Leutnant,” said one of them nervously, standing stiffly to attention, and Rex gathered the impression that von Henkel was no easy master to work for.

“I just met him on the tarmac,” continued Rex, as if impatient to depart. “He was in a hurry and could not return, but he forgot to ask you to do a small job for him; have you any red dope?”

“Jawohl, Leutnant.”

“Good. He wants the axle hub of each machine painted red, a moment’s work, and then you may go. Oh, and you are not to mention this to a soul, he says. Do you understand?”

“Jawohl, Leutnant.”

“Gootnacht.”

“Gootnacht, Leutnant.”

As Rex was about to turn something made him glance up at the window through which he had been peering only a few moments before. Framed in the dim light, his lips parted in a sardonic smile, was the face of Captain Fairfax. Fortunately the mechanics had their back towards him and could not see him. Before Rex had recovered from the shock the expression of Fairfax’s face changed to one of surprise, and then it sank down out of sight. Rex thrust his hand in the pocket of his jacket and marched stiffly towards the open door. He knew that the game was up, that before he could reach the door Fairfax would be there and would have given the alarm. Well, he’ll get what’s coming to him, thought Rex grimly, resolved that the instant Fairfax appeared in the doorway he would shoot; that would mean one spy less, anyhow. With his hand firmly grasping the butt of his revolver he reached the door, but still Fairfax had not appeared. For a moment he paused in uncertainty. Where was Tony? Coming to a quick decision, he turned, and, crouching low, revolver in hand, sprang round the end of the hangar. Again he pulled up in amazement; there was no one in sight. Bending low he ran down the side of the hangar and round to the back. A figure rose up in the darkness just in front of him, and his finger was already tightening on the trigger when Tony’s voice, quivering with excitement, broke the silence.

“I’ve got him, whoever he is,” he said with a quick sibilant hiss.

“Didn’t you see his face?” whispered Rex, taking a pace forward. His foot struck against something metal and he stooped and picked it up. It was an electric torch. “Look!” he whispered, and, shielding the rays with his coat, turned the light on the face of the unconscious man. “Look,” he grunted again, grimly, as the beam revealed the pale face of Fairfax, and he heard Tony’s swift intake of breath. “What did you do, Tony?” he asked.

“I saw someone peeping in. I was behind there in the bushes and he didn’t see me. It seemed certain that he couldn’t be up to any good, so I crept up behind him and landed him one on the back of the nut with my gun.”

“Good—hark!”

Footsteps were approaching. Thrusting the torch into his pocket Rex, with Tony at his heels, dashed away into the undergrowth which skirted the road behind the hangars. Hardly daring to breathe they flung themselves down and lay still until the footsteps had halted. There was a cessation of sound in the hangar and Rex caught a few words of a sharply-snapped order. “It’s the orderly officer doing his rounds,” he muttered. Presently they heard the sound of military boots receding again down the tarmac in front of the sheds.

“It’s all right, he’s gone,” breathed Rex in Tony’s ear as he rose to his feet.

Like an Indian he crept back to the rear of the hangar where Captain Fairfax was still lying prone on the ground, and risked another peep into the hangar. Only one mechanic remained, and he was just painting the last of the four axle hubs. Hurrying back to Tony, Rex caught him by the arm and stood listening intently for a moment. “I should like to have a squint into the mess,” he whispered, “but I don’t think we dare risk it. We’ve done enough for one night. I expect von Henkel is down there in the mess with the others, but Fairfax is here and I should like to know how he got here. Did he come in the S.E.5? And if he did, where is it? That’s what I should like to know. It isn’t in the sheds and it isn’t on the tarmac. Never mind, let’s get along, we’ll think about that later.”

Taking all reasonable precautions they returned to the field where they had left the Hannoverana, and a glance showed them it was still in the same place; two soldiers with fixed bayonets were standing on guard by the propeller. Several others were examining the sinister-looking machine with interest, the Unter-Offizier standing some little distance away in conversation with another uniformed figure. Rex hurried up to them.

“Everything all right, Sergeant-Major?” he asked brightly.

“Yes, I think so!” replied a voice that brought Rex to a dead stop and sent little icy shivers running down his spine. Almost as if it had been timed the moon burst out from behind a cloud and flooded the scene with a pale light. Rex looked up into the smiling face of Leutnant von Henkel. His lips went bone dry and his mind raced at feverish speed, but before he could act the Leutnant had continued, “Why, hullo, Wistmann, it’s you, is it?” he said. “I hear you have had a forced landing—engine trouble. I don’t think anybody has touched the machine. Have you got what you want from our workshop?”

“Yes, thanks,” nodded Rex, his brain in a whirl. Why didn’t the fellow get it over and done with? Why the suspense? He had but to say a word and a dozen hands would come forward to drag them away to a place from which their last journey would be to face a firing party before a blank wall. In order to gain time and to bear out his story, he lifted up the engine cowling and tinkered about for some minutes with the sparking plugs. “She should be all right now,” he said casually, determined to carry on the bluff to the bitter end.

“Good. I hope you’ll get back all right,” said von Henkel, stepping back. “We had word at the mess that there was a machine down here somewhere and Hauptmann von Rasberg asked me to walk along and see if we could do anything. Cheerio—happy landings.”

Unable to believe his ears Rex climbed into the cockpit, while Tony, behaving like a man in a dream, took his place at the propeller. To say that Rex was dazed would be a very inadequate description of his feelings at that moment. Von Henkel’s manner was utterly incomprehensible to him, unless, of course, Fairfax had not reported the hold-up incident in the hangar, which seemed incredible. “Contact!” he said mechanically, still hardly daring to think that von Henkel intended letting them go. The Mercedes engine started off with its usual powerful roar and Tony hurried round to his seat. With a parting wave of his hand Rex swung round into the wind and a moment later was in the air heading back for the lines and safety.

For some time he was unable to think clearly, so great had been the shock of first seeing von Henkel standing by the machine, and then his friendly attitude which terminated in allowing them to depart, apparently the best of friends. The whole thing was hard to believe. That Fairfax had not reported the incident in the hangar when he had been robbed seemed the only possible explanation. What curious motive lay behind his failing to take such an obvious step was beyond Rex’s capacity to solve, he decided, as he threaded his way between the inevitable searchlight beams and raced across the line.

Tony had said nothing. Only once, when Rex had looked round at him, he shook his head sadly and threw up his hands with a gesture of amazement as if the whole business was beyond him, too—as indeed it was.

“Well, we haven’t wasted our time,” observed Rex, after they had put the machine in the shed. “We’ve learned something and we’ve done something. The Major was right when he said that information was leaking back to the enemy; it is certainly doing that. The black stripe business is a good example. Those bands must have been painted on yesterday, which means that the Boche knew all about the order almost as soon as it was issued. Taking the numbers of those machines would not have helped us either; they’ve both been repainted. The paint on them was still wet when we were there—I made a point of looking. Still, if those red marks on the hubs aren’t spotted they will tell us all we need to know, although we shall have to fly fairly close to see them, but that shouldn’t be very difficult.”

“What on earth made you think of painting the hubs?” asked Tony suddenly.

“Goodness knows,” replied Rex, “it was a sort of inspiration. When that confounded dog rushed out and started kicking up that row I thought it was all up and no mistake; the only thing to do was to play a big bluff. I took the bull by the horns and walked straight into the hangar. I had to say something, and a row of coloured dope-tins in the corner no doubt suggested the idea to me. The main thing is, it worked. I can’t understand von Henkel, though. You could have knocked me down with a feather when I saw him standing there; but let us muster our facts, the things we know, and see how they look.

“First of all, we’ve discovered British machines on a German aerodrome, and we know that they are being used by the enemy. Why? We don’t know for certain, but we have every reason to suppose that they are used for carrying people to and fro between the German back areas and our own. When do they operate? I should say by day, or there would be no need to use them at all—they might as well use Boche machines if they are doing it by night. Let us say that it sometimes happens that a job has got to be done in a hurry, something really urgent. If it is in the daytime they simply wheel out one of our machines, knowing that it can do pretty well as it likes over our side of the line without attracting attention. That means they must have a landing-ground somewhere, and when we know where that is we shall know a lot. That’s what we’ve got to find. When we’ve spotted that we can put the whole thing in Trevor’s hands. We learnt something else to-night. Von Henkel is flying those machines—that’s his job. At least, it is either him or Fairfax, but I suspect that Fairfax only works in the S.E.5. Both von Henkel and Fairfax are in this game up to the eyes. Taking it all round we haven’t done so badly. We know they are using our machines, we know where they are, and we know at least one of the pilots. Fairfax is the big conundrum. It’s hard to see just where he fits in. Are there two Fairfaxes, two men so much alike that we can’t tell them apart, or is Fairfax, who is a trusted officer at Divisional Headquarters, the same Fairfax as we think we see over the lines? Everything points to the latter, yet there are one or two posers that need answering if that is the case. One is that we have left Fairfax in Germany, yet when we got home he was here. He can’t be in two places at once. Secondly, and this is the thing I can’t get over; the day we took those plans off him someone came and got them back, and then went off in an S.E.5. Who else could it be but Fairfax in that machine, yet while that machine was in the air he was in his office at Divisional Headquarters? When I rang up and they told me he was in, it fairly took the wind out of my sails. And now there is this last business. It begins to look as if he didn’t say a word about us holding him up over at Varne. Why? I don’t know, but if he had so much as opened his mouth von Henkel would have been one of the first to hear about it. The fact that he was perfectly friendly to-night definitely proves that he knows nothing about that affair. It may be that Fairfax thought he could get those papers back—as indeed he did—without saying a word for fear of getting into trouble himself for letting us get away with them. The German Higher Command does not suffer bunglers gladly; all the same Fairfax knows us, and he has only to open his mouth to get us shot if they ever lay hands on us. Well, that’s how things stand at present, but I fancy they will begin to sort themselves out before long. One thing is certain, we’re skating on jolly thin ice; one false move and no one will know what happens to us, and that is as likely to happen over this side of the line as the other. They’ve got men over both sides, don’t forget, and one of them at least knows all about us—Fairfax. Well, I shall know more about him to-morrow.”

“To-morrow—what are you going to do to-morrow?” asked Tony in surprise.

“Wait and see,” replied Rex mysteriously, “—but let us get some sleep, I want to be on the move early.”

It was about nine o’clock the following morning when Rex and Tony stepped into the squadron car which they had requisitioned. With them were two mechanics of the squadron, a fitter and a rigger, who Rex knew could be trusted. They drove to Maranique and made their way to the hangar which housed the Hannoverana, where Rex set the mechanics about the duties for which he had brought them, which included a quick overhaul of the machine and the painting out of the existing numbers which were to be replaced with new ones.

“It is just a precaution in case Boche machines get instructions to keep an eye open for us,” explained Rex to Tony.

Leaving the mechanics at work they re-entered the car and made their way slowly through lines of transport to Divisional Headquarters, which were situated on the outskirts of Amiens. Leaving the car at the gate they entered the big house that had been commandeered by the authorities.

“Which is Captain Fairfax’s room?” Rex asked a hurrying orderly.

“The third on the right, sir,” replied the man.

“Is he in?”

“Yes, sir.”

Rex looked at Tony and grimaced. “Good Lord, I hope we’re not making a mistake,” he whispered dubiously. “I should have thought that crack on the head you gave him last night would have put him in hospital for a week.”

Just as they reached the door it was flung open and Fairfax, smiling and debonair, appeared on the threshold.

“Hullo—hullo,” he cried brightly, “what brings you here?”

“Hullo, Fairfax,” grinned Rex, “nothing in particular. I’ve just been down to Amiens to have a tooth out, and passing here on my way back I thought I’d look you up. Have a cigarette?” he concluded, offering his case, “—look out! Sorry,” he cried, as the heavy silver case slipped through his fingers and fell with a crash on the stone floor. Fairfax stooped quickly, picked up the case and handed it back.

“Hasn’t hurt it,” he observed, glancing at the hinges as he passed it over. “Well, it was nice of you to look in, but I’ve got to rush off now. See you next guest-night I hope—cheerio.”

With a parting wave of his cane he strode off and the two boys returned slowly to their car. “If that man’s a spy, I’ll eat my hat,” muttered Tony, shaking his head doubtfully as they threaded their way along the road. “If he is, then the man must be a marvel to act like that, knowing that we know what we do know.”

“We shall soon know still more about it,” observed Rex grimly, as he pulled up at Neuville and hurried towards Wing Headquarters; but instead of entering as he usually did through the front door, he made his way to a door at the end of the building, through which a number of N.C.O. clerks could be seen at work. “Who is in charge here?” he asked quietly as he entered.

“I am, sir,” said a Sergeant-Major stepping forward.

Rex took him on one side. “I am working with Major Trevor,” he said in an undertone.

“Yes, I know that, sir,” replied the Sergeant-Major nodding.

“Good, that will make it easier,” answered Rex. “Tell me, have you a finger-print department here?”

“Yes, sir.”

“Good again. Now I want you to do a little job for me—right away if you can manage it.”

“Certainly, sir, come this way,” replied the Sergeant-Major at once, leading the way to a small room at the rear.

“Quite a laboratory, eh?” observed Rex, noting the rows of chemicals and apparatus that stood about.

“Quite, sir,” agreed the N.C.O. “We have to do a lot of testing for invisible inks, you know.”

Rex laid his cigarette-case on the table. “I want you to examine the finger-prints on that for me, please,” he said.

The Sergeant-Major opened the case flat on the table and dusted it lightly with some powder which he took out of a drawer, and then bent over it. “There are two sets of prints here, sir,” he said.

“Yes, one of them is my own. You had better take my finger-prints so that you can identify them, and then I want you to have a good look at the other.”

Rex pressed his fingers on an inking pad which the N.C.O. brought, and then made a clear impression on a piece of white paper. “And now I want you to have a good look at this,” went on Rex, and taking out of his pocket a silk handkerchief, unrolled it to disclose the metal torch which had been dropped by Fairfax behind the German hangar the previous night. Again the Sergeant-Major busied himself for a moment while Tony, suddenly understanding Rex’s action, leaned forward quivering with excitement.

“Two sets again, eh?” observed the Sergeant-Major. “I can see yours, but it is fairly smothered with the others.”

“Compare them with the case,” said Rex quietly.

The Sergeant-Major placed the two articles side by side and picked up a large magnifying-glass. “They are the same finger-prints on both articles,” he said without hesitation.

“Ah!” Rex took a deep breath. “Thank you, Sergeant-Major, that was what I wanted to know. These other finger-prints are not known to you by any chance, I suppose?”

The Sergeant-Major bent closer and subjected the marks to an intense scrutiny, and the boys, watching him closely, saw him start and a curious expression spread over his face. Without a word he crossed the room, unlocked a metal safe, and took from it a bulky volume. He placed the book on the table and turned the pages over rapidly until he came to the place for which he was evidently looking. He laid the cigarette-case on the book. Rex, peering over his shoulder, saw long rows of finger-prints and thumb-prints, with little marginal notes against each.

“Yes, sir,” said the Sergeant-Major in a curious voice, “we know those prints all right and we should very much like to find the owner of them.”

“What is his name?” asked Rex in a voice which he tried hard to keep steady.

“At the Wilhelmstrasse he is known as Number 1473,” replied the Sergeant-Major grimly, “but we know him as Hauptmann Baron Gustav von Karnhofen, the cleverest secret service agent in the German Corps since the master spy Wilhelm Stieber. Do you know where he is, sir?” asked the Sergeant-Major eagerly.

A slight sound made them all look round; Captain Fairfax was standing in the doorway. For a moment Rex stared unbelievingly, and then dashed at the door; but he was too late. Before he could reach it the door was slammed in his face; there was the sound of a key being turned in the lock outside and Rex tugged at the handle in impotent rage.

“The window,” cried Rex, “the window!”

It was the work of a moment to fling up the sash and slither through the narrow opening. For a moment they all stood hesitating, and then, “Hark!” cried Rex.

The sound of an aero engine ticking over was borne to their ears from the direction of the hangars, and even as Rex started off towards them the sound became a roar and he stopped with a gesture of dismay. An S.E.5 soared into view above the roof. It made a graceful turn, dipped towards them in a mocking dive, and then zoomed high into the sky. “There he goes,” said Rex bitterly.

“The Hannover—let’s go after him in the Hannover!” cried Tony.

Rex laughed ruefully. “Don’t be a fool, Tony,” he said. “He’ll be halfway home before we can start the engine. The bird has flown—but we happen to know where his roost is.”

*      *      *      *      *

“The more I see of this, the more I see that the Major was right,” observed Rex gloomily. “It is a deep game we are playing. You can’t trust anybody; even that Sergeant-Major might have been a spy.”

Tony looked at him incredulously.

“Why not?” said Rex with a shrug of his shoulders. “I’m ready to believe anything—why look surprised? If you read your history you will see that Generals have been traitors before to-day.”

“If that is so we might as well pack up,” muttered Tony, “we can’t go about arresting Generals.”

“I didn’t say we could, you ass,” retorted Rex, “but there, it is no use kicking ourselves now. We acted for the best. How on earth were we to know that Fairfax was coming over to Wing H.Q.?”

“He wasn’t,” observed Tony drily. “He followed us over if the truth was known, to see what we were doing. He didn’t believe our tale about dropping in casually this morning.”

It was Rex’s turn to stare. “Of course,” he muttered. “What a fool I was. Fairfax is an expert at the game and we’re just a pair of doddering amateurs.”

“What are you going to do?”

“I’m going to fly over in the Hannover once more to see if I can spot anything. We may catch the S.E.5 on the move again. That chap’s got nerve enough for anything; it wouldn’t surprise me if he flew over here and landed at Maranique this afternoon,” said Rex bitterly. “When I come back, we had better go and lay the whole case before the Major; it’s only fair to do that—it’s getting a bit too big for us,” he concluded.

“All right, well, let’s go and change and get the Hannover,” agreed Tony. “Our fellows should have finished their overhaul by now.”

Ten minutes later they were in the sky, dodging the usual archie-bursts from the British guns as they raced across the lines. A lot of heavy cumulus cloud was swinging majestically across the heavens and Rex headed towards it with the object of taking cover until they were well over German territory. For some minutes they picked their way among the cloud-banks as they edged their way cautiously towards Varne. A large detached cloud was immediately above them and Rex watched it suspiciously. Was it, or was it not? Had it been a trick of the imagination, or had he seen a dark grey shadow flit across a thin place in the opaque mist?

Even as he swerved away something solid detached itself from the cloud and hurtled down at them. It was an S.E.5. A double stream of flame was blazing from the two guns mounted on the engine cowling, and with a wild yell of warning Rex flung the big machine over in a half-roll to escape that devastating hail of lead. As he came out of it he looked around swiftly for the attacking machine and saw it pulling up in a terrific zoom under his elevators.

Tony, hanging on like grim death in the rear cockpit, was trying to see if there were any markings on the S.E. that he could recognise. If it was Fairfax he would shoot him down without hesitation, but if it was not, then he was helpless. He could not shoot down one of his own side, who was behaving fairly and courageously according to the rules of the game, even in self-defence. Unfortunately the machine was head-on to him and he was, therefore, unable to see any identification marks except the black stripe on the centre section, which was useless as a guide, for he knew that it would be on Fairfax’s machine as well as on every S.E. along that sector of the front.

Pale with excitement and apprehension he pumped a shower of lead from his Parabellum guns in the direction of the S.E. in the hope that it would drive him off, but without effect. He saw Rex’s face turn pale with anxiety as the S.E.’s bullets began ripping through the Hannover. Something struck his gun-mounting with a loud whang-g-g, and a fragment of metal scored the side of his face. Spang-g-g—flack-flack-flack went the bullets through the black-crossed machine.

Tony dropped his gun and struck Rex violently on the shoulder. “Down!” he screamed. “Down—down! Go down—it’s our only chance!”

But the S.E. pilot was evidently an old hand at the game and had no intention of allowing his victim to escape. The German gunners on the ground, seeing the perilous plight of one of their own machines, sent up salvo after salvo of frantic signals to attract any other German aircraft in the vicinity, but in vain. They dared not shoot at the S.E. for fear of hitting their own machine.

With his face set and white, Rex flung the Hannoverana into a steep sideslip, straightening out and stunting—as far as that was possible with such a big machine—when the S.E.’s fire became too hot. Burst after burst poured into the Boche machine at almost point-blank range, and Rex knew that they were being literally shot to pieces. The S.E. pilot, finding that his opponents made no attempt to return the fire, came in closer and closer with every burst. The German plane was in a terrible condition. One inter-plane strut was hanging by a piece of wood no thicker than a finger; lacerated fabric streamed out behind and the instrument-board was a ruin of mangled glass and metal. The engine gave a choking splutter and a cloud of white vapour swirled away aft. A bullet ripped through the gravity tank and a shower of petrol swept over Tony. Metal spanged against metal. Something slashed against Rex’s goggles with a force that nearly stunned him and he tore them off mechanically and flung them away. He could still hear Tony’s guns stuttering their little staccato bursts, and wondered if his observer was at last deliberately shooting at the S.E., and why the flash of his guns did not set fire to the petrol which was over everything. He knew the end had come and glanced down to see where they would crash. They were nearly on the ground and beneath them lay a ploughed field bounded on all sides by trees. As far as the eye could see there was not a field large enough to get the machine down without a crash, even if it did not break up in the air. The sound of shooting suddenly ceased and a lightning glance over his shoulder revealed the S.E.5, dangerously low for so far over enemy country, climbing for height for all it was worth, pursued by a veritable maelstrom of raging archie. Rex’s propeller had stopped and the only sound he could hear besides the thunder of the guns on the ground was the wind screaming in his wires. “Tony!” he yelled frantically. “Tony!” and breathed a deep sigh of relief as he heard Tony’s answering, “Hullo!”

PULLING UP IN A TERRIFIC ZOOM UNDER HIS ELEVATORS

“I’m going to crash!” he shouted. “Strap in. Lift up your knees and cover your face—hold tight!” The Hannoverana lurched drunkenly as the pilot sideslipped steeply over the trees that bordered the field, in a praiseworthy attempt to make a landing, but it was an impossible task. The pilot fishtailed frantically to lose height as he flattened out, but the trees at the far side of the field rushed towards him. He aimed the nose of the machine between two of them so that the wings would absorb some of the shock; it was better than hitting one head-on. At the moment of impact he lifted his feet to prevent them being trapped, and buried his face in his arms. There was a tearing, rending, splintering crash as the machine folded up around him. He was up in an instant, clawing his way like a madman out of the wreckage. “Tony—Tony, where are you?” he cried wildly as he fell clear.

“I’m here,” gasped the observer breathlessly. He was hanging upside down on his belt, but he got the safety strap undone and fell head first among the tangle of wood and fabric.

“Quick!” yelled Rex, seizing him by the collar and dragging him out backwards. They were just in time. There was a dull “whoosh” as the petrol-soaked mass took fire, and with their hands over their faces they raced away from the blazing inferno. A troop of Uhlans were galloping across the field towards them.

“Well, it looks we’re out of the fire into the frying-pan,” muttered Rex aghast. “We are in Germany now with no way of getting out of it, and if Fairfax has blabbed—but don’t let’s worry about that, we aren’t dead yet. We’ve got to play German as we’ve never played it before, and watch for a chance to make a bolt for it. If we can get into the woods and get rid of these uniforms it might not be so bad even if we are caught later on. If we can get far enough away from Varne, they might take us for two ordinary airmen who have been shot down.” He swung round on his heel. “Where is the nearest aerodrome?” he demanded gruffly of the Unter-Offizier at the head of the Uhlans.

“Varne, Leutnant, not far away,” replied the German. “Are you all right—we saw the fight and thought you must have been killed?”

“Yes, we’re all right,” replied Rex irritably.

He was thinking swiftly, for he had no idea that they were so close to the place, which, above all others, they were anxious to avoid. “Nein—nein,” he said again to the Sergeant-Major who was mumbling something about fetching an ambulance. “We are only shaken—that schweinhunt Englander——” he broke off to stare at another group of men hurrying across the field. It consisted of five or six officers in the uniforms of the German Flying Corps, who had apparently just alighted from a big car that was standing near the gate. Rex recognised them at once as pilots he had seen at Varne; von Henkel was among them and his heart sank.

“Are you hurt?” von Henkel cried, hurrying up. “We saw the scrap from the aerodrome and rushed over to see who it was, but to tell you the truth we did not expect to find anything but cinders. You’re lucky to be alive, you two. Well, nothing much can be done with that,” he added, pointing to the flaming wreckage behind them, “we may as well be going.” The whine of bullets exploding in the heat of the flames hastened their departure.

Rex’s brain was working at lightning speed as they plodded slowly towards the gate, and but for one significant glance at Tony, he had no opportunity of conveying his impressions at this new development, for the German pilots crowded around and plied him with questions concerning the combat. Rex heartily cursed the British pilot in fluent German, which made the others laugh, but his outburst was not altogether acted. It might, of course, have been Fairfax, but if not, the fellow had placed them in a frightful predicament. As they entered the car, on the pretence of looking at the slight flesh wound in Tony’s face, he managed to whisper, “Keep close. If Fairfax is over here the game’s up. If not, stand by to make a bolt for it in one of their machines.”

He took his place in the car and they whirled away to the aerodrome to meet whatever fate held in store for them. The next ten minutes seemed the longest ten minutes Rex could ever remember. The anxiety of not knowing whether Fairfax was on the aerodrome waiting to denounce them the moment they put in an appearance was almost unbearable. They arrived at last, and still chatting apparently unconcernedly they entered the officers’ mess. One glance and their worst fears were realised; several officers were seated at the table drinking coffee after a late lunch. At the head of the table, facing them, was Fairfax. Rex never forgot his sensations at that moment; time seemed to stand still as he awaited the inevitable exposure. Fairfax was stirring his coffee with a quiet air of composure as he listened to another officer of the party speaking. He glanced up casually as they entered the room, and, as their eyes met, Rex saw the other’s gleam curiously; but the sign of recognition passed instantly and he was talking to the man on his left, still stirring his coffee, as though nothing had happened.

Rex felt his knees go weak from shock and reaction. As in a dream he heard the voice of the mess waiter, and reached mechanically for the glass of cognac held out to him by the station medical officer who had hurried to the scene when he heard of their arrival.

“Take that, my boy,” he said kindly. “You need a bracer.”

Rex certainly needed something at that moment; he threw the fiery liquid back into his throat with a grimace and a word of thanks, and looked around to see how Tony fared. To all intents and purposes he was thoroughly at home, recounting their adventures for the benefit of the officers who had not seen the combat. Hauptmann von Rasberg hurried up with a gruff word of congratulation on their narrow escape. “What squadron do you come from?” he said. “I must ring them up and let them know you are safe.”

Taken aback for a moment Rex did not lose his head. “97th Truppenflieger-Abteilung (Army Corps Squadron), sir,” he replied without hesitation, “but I’d rather ring up myself, if you don’t mind.”

“Certainly,” replied the German C.O. to his unutterable relief, for he knew, of course, that if the German once got in touch with the squadron he had named, the cat would be out of the bag with a vengeance. “You will find the telephone in my room there,” went on von Rasberg, pointing to a door in the corner of the room.

Rex hurried to the telephone and put a call through to the Army Corps Squadron. “Is Leutnant Adolf Grosbach there?” he asked as he was switched through, and as the name was one of his own invention it did not surprise him to hear the telephone orderly reply in the negative. “Very good,” he said. Out of the corner of his eye he saw a faint shadow move on the floor near him, and he stiffened in his chair. “Yes, exactly,” he went on without a pause, “no, neither of us was hurt. Koepler has got a scratch on the face—nothing to speak of—but the machine is burnt out.” Ignoring the orderly’s frantic demand to know what he was talking about, “Very good, sir—yes, sir—to-night, sir—good-bye,” he concluded and hung up the receiver. He rose to his feet and turned round. Hauptmann von Rasberg was standing in the doorway watching him.

“Did you get through all right?” asked the German.

“Yes, thanks,” replied Rex easily, wondering how much he had heard.

The Hauptmann nodded. “You had better stay and dine with us and then I’ll send you home by car,” he said. “Leave me now, I have work to do.”

Rex returned to the mess and caught Tony’s eye. He noticed that his partner was beginning to look anxious and he strolled across the room to join him. “It’s all fixed up,” he said, “we’re staying here to dinner at the C.O.’s invitation. Let’s take a stroll round the tarmac.”

“Well, what do you make of it?” he asked a few minutes later when they were alone.

“I can’t make anything out of it,” replied Tony hopelessly. “It beats me altogether—it’s fantastic. I know one thing, though, I shall be jolly glad to be out of this; we’re in the worst mess we’ve ever been in. I don’t know what Fairfax is playing at. He’s deep, that chap, and he’s got some scheme on foot or we should have been in Lille prison by now. One thing is certain, Fairfax or no Fairfax, this can’t go on much longer; it only needs someone who knew Wistmann or Koepler to roll up and——”

“I wish you’d try and think of something cheerful for a change,” broke in Rex. “It’s all right at the moment and that’s the main thing. We’ve got to get a machine by hook or crook, and I’ve got my eye on that green Rumpler over there—the one those mechanics are working on. The moment they leave her I’m going across to start it up.”

“Bah! You don’t think you can get away with that,” sneered Tony. “Fairfax is watching us like a cat watching a mouse; there he is over there, now, see him? He’s not worrying much. He knows he’s got us stone cold where he wants us. The first move we make for a getaway and it will be a file of men with fixed bayonets for us.”

“Well, he can only stop us,” said Rex desperately, “and we should know where we were. Sitting still will get us nowhere.”

“A move towards that machine will get us somewhere, and quickly,” retorted Tony. “It will get us behind the bars of Lille prison with nothing to look forward to except a nice little shooting party before breakfast in the morning. We’re being watched, I tell you, and Fairfax isn’t the only one.”

Rex looked around cautiously. “You’re right,” he said briefly. “Fairfax is watching us and so is that fellow over there on the left. He’s pretending to be tinkering with that engine, but he’s got his eye on us all the time. Well, I’m not going to hang about here doing nothing; if it’s coming let’s get it over. I’m sorry I’ve landed you in this mess, old lad, but——” he shrugged his shoulders. “It’s the fortune of war,” he concluded philosophically. “Come on, those chaps have finished the Rumpler, if we can once get her in the air we will at least give them a run for their money.”

Together they strolled casually towards the big green machine. “Get to the prop., Tony,” said Rex tersely. “If she’ll start first swing, we might get off before they can reach us even if it means starting with a stone-cold engine.” He leapt nimbly into the pilot’s seat. “Suck in,” he snapped, “and make it lively.” He took a swift glance towards the tarmac and his heart turned to stone; two officers were walking quickly towards them. It was von Rasberg and another officer whom he did not know, but obviously an officer of senior rank by the servile way in which von Rasberg was listening to him.

“Contact!” cried Tony desperately.

“Contact!”

There was a sharp report as the engine backfired.

“Try her again, Tony,” called Rex, deadly calm.

There was a dull swishing sound as the prop. swung round, but it stopped again with a quivering jerk. There was no time for another attempt.

“What do you fellows think you are doing?” asked von Rasberg coming up.

“Oh, we were doing nothing, sir, so I thought I’d try this machine,” said Rex evenly. “I’ve always wanted to fly a Rumpler,” he added.

The other officer said something to von Rasberg in an undertone which Rex could not catch, and then, aloud, “Good, I am always pleased to see officers so keen on their work. Take it by all means, but don’t be long—no, not you,” he added quickly, as Tony took a step towards the rear cockpit. “I do not think it is right for officers to carry passengers when trying a new machine. If there is an accident we lose two officers instead of one. Go across to my chauffeur and tell him to bring my car round, Colonel von Hartzmann’s car.”

Tony stiffened to rigid attention, saluted with a little bow in the German fashion, and departed in the direction of the hangars.

Rex watched him go with his brain whirling. Well, he decided, he’d started it and now he would have to go on with it. He beckoned to a mechanic to swing the prop. for him. At the third attempt the engine started and he taxied slowly across the aerodrome into position for taking off. If only Tony was in the back seat now, he pondered sadly, but he wasn’t, and there was an end to it. What rotten luck that the engine wouldn’t start. How could he get him into the machine? That was the question. He took off and circled the aerodrome to think things over. A thousand feet below he could see Tony standing outside the officers’ mess and could imagine the wistful expression on his face. Suppose I landed again, mused Rex, I wonder if he could sprint out and jump aboard before they could stop him? It might be done, but it was taking a terrible risk, he decided. Failure would inevitably mean disaster. There must be some other way. Yes—he had it. He banked steeply and swung round in the direction of Salsec aerodrome, the headquarters of the 17th Jagdstaffel. He knew the place well by sight from the air, and as far as he could remember it was not more than ten or fifteen miles away.

Ten minutes later he made a good landing on the aerodrome of the German fighting squadron. He taxied close up to the hangars, and, leaving the engine ticking over, walked boldly to the small building at the end of the hangars which he took to be the squadron office. He rapped on the door and in reply to the curt, “Enter!” opened it and stepped across the threshold. “Leutnant von Grossmann, sir,” he said smartly, giving the first name that came into his head.

The officer at the desk eyed him coldly. “Well, what is it?” he asked shortly.

“I am on a test flight, sir, but I have lost my bearings; I have landed to ask where I am.”

“Salsec,” snapped the other. “Go to the map-room and you will see where you are—through there.” He nodded towards a corridor and then went on with his work without another glance.

Rex departed in the direction indicated, but instead of entering the map-room he made his way to the ante-room adjoining the officers’ mess. As he hoped, the room was nearly empty for he knew that at that time of day most of the pilots would be in the air. Two or three officers were sitting reading near the fire, but they took no notice of him. “Is there a telephone handy?” Rex asked the nearest.

“In there.” The officer pointed to a door with the stem of his pipe. Rex opened it and found himself inside a small cabinet and breathed a deep sigh of relief as he picked up the instrument. “I want the officers’ mess—Varne, please—and quickly,” he told the operator.

“Hullo, is that Varne?” he asked a moment later as a voice came over the line. “Good. I am speaking for the officer commanding 97th Army Corps Squadron. I wish to speak to Leutnant Koepler. Yes, yes, he may be on the tarmac—find him at once, please.” For two minutes he waited, burning with impatience, before Tony’s answering voice came over the wire. “Tony,” he said quickly, “listen. Get behind the hangars and try and sneak off. Make for that big field about a mile north-east of the aerodrome—the one I pointed out to you the other day as a good emergency landing-ground. I shall be there in fifteen minutes with the machine and I shall wait until you come. Don’t hurry if it means taking a risk, but get there as soon as you can. Got that? Good-bye.” He hung up the receiver, pulled himself together before re-entering the room, and then strolled out as unconcernedly as possible. It was not until he was once more back in the cockpit of the Rumpler that he realised how great had been the strain of the last few minutes. He was as cold as ice and the hand that held the joystick was trembling slightly in spite of his efforts to steady it. He took a deep breath, taxied out, and took off. The luck’s in, he told himself jubilantly as he headed for the rendezvous. If only Tony can get away, and that should not be very difficult, the rest will be easy.

Reaching the field he circled for a moment to pick out the best place on which to land, and then glided slowly down. His wheels touched the soft turf, and without waiting for the machine to finish her run he taxied round into position facing the wind for the take-off. Standing up in the cockpit he looked anxiously around; not a soul was in sight. He did not dare to switch the engine off, but left it ticking over, praying fervently that no one would hear it and come to investigate. The minutes passed on leaden wings and the strain of waiting became almost unbearable. He was about to get out and walk up and down to relieve the tedium when there was a quick rustle in the hedge behind him and Tony burst through.

“Get in,” snapped Rex, and before Tony was properly in his seat he was racing, tail up, across the field. As he zoomed steeply over the trees at the end, a cheer of joy and relief broke from his lips. Tony leaned over and patted him on the shoulder. “Pretty good!” he yelled. “We’ve done it.” Turning, he waved a mocking farewell to the aerodrome over which they were now passing, but the next instant his smile of victory was replaced with an expression of utter horror. A new note had crept into the engine and it began to misfire badly. Rex needed no telling what had happened—they had run out of petrol! He had taken the Rumpler before the tanks were refuelled. He made a gesture of utter despair and began to glide down towards the aerodrome, the only possible landing-ground within reach. A moment later their wheels touched, and the Rumpler ran slowly to a standstill in front of the hangars.

“What luck,” ground out Rex between set teeth, “what filthy abominable luck! Look who’s waiting for us. Well, the worst they can do is to shoot us.”

Tony, following Rex’s nod, looked. Standing on the tarmac, not twenty yards away, was Colonel von Hartzmann. Beside him, wearing an expression that boded no good for them, was Hauptmann von Rasberg. Behind them, a little distance away, smiling grimly, stood Captain Fairfax.

Now there comes a time in the most adverse circumstances when things look so bad that they could not possibly be worse, and the reaction often takes a curious form of relief. And so it was with Rex at that moment. At the sight of the group standing on the tarmac, following the mental and physical strain of the last few hours, all trace of nervousness and anxiety left him. The worst had happened, so there was no need to worry about it any more. A broad grin spread over his face. “Well,” he said loudly, “here we are,” and hummed a popular tune as he climbed stiffly from the cockpit.

The Colonel took a pace or two nearer and his eyes narrowed ominously. “Did I tell you you were not to take a passenger in that machine?” he enquired in a voice which cut the air like a whip lash.

“Yes, sir, but——”

“But! You dare to answer me back,” stormed the irate officer. “Don’t you understand orders?”

Rex closed his teeth like a trap.

“Did I say you were not to take a passenger?” snarled the Colonel, raising his arm as if to strike him in his rage.

“Yes, sir.”

The Colonel was quite right. He had disobeyed orders and even if he had been what he pretended to be, that is, a German officer, he would deserve punishment. “I ought to put you both under close arrest,” snapped the Colonel harshly, and then with a sudden change of tone, “Well, how did you like the machine?”

“A nice, comfortable machine to fly, sir, thanks,” replied Rex evenly.

“You think so? Good. Have you ever done any night-flying?”

“Certainly, sir,” answered Rex at once.

The Colonel nodded slowly and a curious smile spread over his face. “Report to me by yourself in the squadron office in five minutes,” he said. “I shall not need you,” he added with a curt nod to Tony, and then swinging round on his heel he strode away closely followed by Hauptmann von Rasberg. Some mechanics wheeled the Rumpler into a hangar and Rex and Tony were left on the tarmac with Fairfax. Nobody spoke, but the tension in the air could almost have been cut with a knife.

“Come on, Tony,” said Rex at last, turning in the direction of the mess.

For a moment Fairfax looked as if he was going to say something, but he changed his mind and they passed without a word.

“Stick around, Tony,” said Rex in a low tone as they reached the squadron office. “I don’t suppose I shall be many minutes,” and turning, he rapped sharply on the door.

“Come in!” snapped a voice.

Rex entered, and raised his eyes to look at the speaker, but they stopped midway as they fell on something that caused an icy hand to clutch his heart. For a moment he could only stand and stare. Just what he expected to find in the room he did not know, for he had had little time to wonder at the Colonel’s demand, but he certainly did not expect to see the thing at which he now stared as if fascinated.

On the table, immediately in front of him, lay an R.F.C. uniform, complete with Sam Browne belt. At that instant it never occurred to Rex that the uniform was anything but his own, which the enemy, probably Fairfax, had fetched from Neuville where he had left it. This is their way of telling me that the game is up, he thought grimly, Fairfax’s idea of a joke. Indeed, as the first numbing shock wore off Rex looked up expecting to see Fairfax in the room, but he was not; only the Colonel and von Rasberg were there.

“Come along, come along,” said the Colonel irritably, “I’m not going to eat you,” and at the sound of the Colonel’s voice it dawned upon Rex that he might have been mistaken about the uniform. With a mighty effort of will he pulled himself together and listened to what the Colonel was saying. He had expected that at least he was in for a severe ticking off and perhaps punishment, but here was the Colonel actually congratulating him on the way he had landed the Rumpler when the engine cut out.

“Yes,” continued the Colonel, “it was an excellent effort. Many a man would have lost his head—and I need men who can keep their heads in an emergency,” he added significantly. “But let me come to the point. As you know, I am in command of the 3rd Army Intelligence Section.”

Rex didn’t know, but he did not say so.

“Lieutenant von Henkel, who usually carries out my most important work for me, has been forced to report sick this afternoon with influenza and I am in need of a pilot to undertake a very important secret mission.”

Rex listened like a man in a trance, and as the fact was slowly forced upon him that one of the heads of the German Intelligence Corps was asking him to undertake a special mission he nearly laughed. It was too preposterous. Again he realised how true were Major Trevor’s words when he had said, “At this game anything can happen.” But the Colonel was speaking again.

“You tell me you have done some night-flying, and Hauptmann von Rasberg tells me you know the area behind the Allied lines along this sector of the front very well.”

“Fairly well, sir,” admitted Rex, wondering what the Colonel would say if he knew just how well he did know it.

“Then your task should be quite simple,” declared the Colonel. “Do you by any chance speak English?”

“I know a few words of the language,” admitted Rex again, restraining an almost overpowering impulse to laugh aloud.

“Very good. It may help you in an emergency. Now this is what I want you to do,” continued the Colonel. “You will take off as soon as it is dark and fly a passenger whom you will find waiting by the machine, to this spot.” He indicated a place on a greatly-enlarged photograph which lay on the table, before him, and Rex bent over to see more clearly. “Here is the main Amiens road,” continued the Colonel, “and here is the Château Neuf. The lake in the grounds forms quite a good landmark and can be seen quite clearly even at night. You will land here.” He pointed to a long open space at the back of the building with the point of his pencil. “My messenger will leave you and you will wait until he returns. All you then have to do is to bring him back here. Have I made myself quite clear?”

“Perfectly, sir,” answered Rex, once more master of himself.

“One more thing,” said the Colonel, “this uniform.” He nodded towards the clothes on the table. “You had better wear these. It is purely a precautionary measure which may help you in the event of a forced landing. That uniform will attract less attention than the one you are at present wearing.”

The Colonel smiled at his own humour and Rex laughed outright.

“That’s all,” said the Colonel briskly. “Bring back my passenger safely and this afternoon’s episode will be forgotten.”

Rex saluted, left the room, and hurried to the tarmac where he found Tony seated on a chock watching a formation of German raiders that were just landing. Seeing Rex coming towards him he rose to his feet and strolled to meet him.

“Well, what was it all about?” he asked breathlessly.

“If I gave you a hundred million guesses you wouldn’t guess right,” said Rex, “and you probably will not believe me when I tell you; I can’t believe it myself yet. Catch hold of yourself and listen to this. As soon as it is dark, I am flying the Rumpler to a spot behind the British lines on a secret mission.”

Tony’s jaw sagged foolishly. “A secret mission?” he echoed stupidly.

“That’s what I said,” repeated Rex tersely. “I know it sounds silly, but it’s a fact. This isn’t a war we’ve got mixed up in, but a fairy tale. Nothing will ever surprise me again as long as I live.” But he spoke too soon, for the day of shocks and surprises was not yet over.

Nightfall found Rex, with his flying-coat concealing the British uniform, in earnest conversation with Tony while awaiting the arrival of his passenger.

“My only regret is that I cannot get you in the machine somehow. Now we know the Château Neuf is the other end of the chain, the headquarters of the Germans who are working over our side of the line, we’ve got the whole thing taped. All we’ve got to do is to get back and put our cards on the table, but it can’t be done; there is more behind all this than we know, and I’ve got a nasty feeling in the pit of my stomach that things are moving swiftly to a climax. We are being watched, I’m certain of that. Well, there is no going back now; we’ve got to play our cards to the bitter end. Whatever happens I shall come back here for you, remember that. Keep handy, you never know when our chance might come to make a bolt for it. Things are quiet at the moment and I feel that it would be senseless to rush into trouble by doing something silly. If we can slip away without stirring up trouble, so much the better, but I am absolutely certain that if you and I tried to get in this machine at this very moment we should both be in the guard-room before we could say Jack Robinson. There is an atmosphere about this place now that I don’t like, although on the surface everything is as nice as pie. Keep your eye on Fairfax, there he is now, standing by the end hangar, watching us. But I expect this is my man coming across. Good-bye, old lad.”

A swift handshake and they parted, Rex to the Rumpler, now ticking over idly outside its hangar, and Tony towards the mess.

Rex’s passenger, muffled to the eyes in heavy flying-kit, hurried to the Rumpler and took his place in the rear cockpit without a word, and his silence did not surprise Rex who was beginning to understand the dire necessity for secrecy in these affairs. They take no chances, these chaps, and I don’t wonder at it, he reflected as he waved away the chocks, and without any further loss of time took off into the starlit sky.

For half an hour he flew on the course he had set, climbing steadily for height until the star-shells of no-man’s-land gleamed below, and then he throttled back and glided quietly over the darkened British reserve trenches and rest-camps beyond. He had no difficulty in picking up the Amiens road and he followed it until he reached the by-road up which the château was situated.

He had seen it many times before and imagined it to be one of the many fine old houses that had been abandoned by its owners when the tide of war swept over it in 1914 and ’15. Indeed, it had suffered badly and as he glided low over it he noticed that a great part of it was in ruins. Not a light showed anywhere.

The field in which he had to land was none too large and he breathed a sigh of relief when the machine ran to a standstill with very little room to spare. He switched off the engine and looked around to find that his passenger was already out of his seat.

“Wait,” was the only word spoken by the man as he turned and hurried off into the darkness in the direction of the château.

Rex hesitated, uncertain as to what action to take. Clearly it was his duty to see what was going on inside the building, but equally clearly he could not afford to make a mistake. A false move now and the spies would scatter and Tony would be stranded in Germany without hope of escape. After a few moments’ indecision Rex decided that whatever the result might be, he must try and find out what was going on in the château, but he had not taken half a dozen paces when a figure loomed up in the darkness near at hand.

“It would be better to stay by the machine,” said a voice, and there was a veiled threat in the ominous words.

“I was just off to see if I could get some help,” replied Rex quickly. “This confounded engine cowling has worked loose and I don’t want it to tear off in the air and smash my top plane; give me a hand, will you?”

Rex climbed up into his seat and groped in a canvas pocket inside the cockpit where he had discovered a few emergency tools, including a large heavy spanner. He returned to the figure standing by the nose of the machine. “Can you feel a bolt under there?” he said, pointing to the underside of the engine cowling.

“Which one?” said the man bending down.

“This one,” said Rex, and brought the heavy spanner down with all his strength on the man’s head. He grunted and collapsed limply on the ground. Rex was on him in a flash. There was no need to hurry for the man lay as lifeless as a log, but Rex was taking no chances. Quickly unwinding his muffler he lashed the man’s arms firmly behind his back, and then, with the leather belt of his flying-coat, he strapped his legs together. Finally he thrust his silk handkerchief into the unconscious man’s mouth and dragged him by the collar to the hedge.

He paused for a moment to listen, but all was quiet, so he strode off quickly towards the building that loomed whitely in the starlight near at hand. He reached some outbuildings and again stopped to listen; he could faintly hear voices coming from the direction of the château, but the house was in darkness. Following the sound he crept stealthily round a corner to the front. All the windows were shuttered in the usual French manner but through one of the shutters which had sagged to one side gleamed a pale shaft of yellow light. By standing on tiptoe Rex could just reach the window and he applied his eye to the narrow slit.

Three men were seated round a table; they appeared to be typical specimens of the French peasant-class, judging by the clothes they wore, but Rex caught his breath as his eye fell on the one farthest away from him and who was facing his way. There was no mistake. It was Hauptmann von Rasberg.

So you were my passenger, eh, I might have guessed it, thought Rex grimly, and then listened intently, every nerve tingling, as von Rasberg spoke.

“I wish he wouldn’t keep us waiting like this,” he was saying in German. “I for one shall be pleased when I get back to where I belong. Hark! He is coming now.”

Rex nearly fell backwards as von Rasberg sprang up and took a quick step towards the very window through which he was watching. He just had time to fling himself back on the ground among the weeds and broken masonry under the window when the window was opened a few inches and the German peered out into the darkness. “Yes,” he said again, “I hear him coming now.”

The faint sound of a motor-cycle rapidly approaching was borne to Rex’s ears. He lay as still as death, hardly daring to breathe, as it drew up on the overgrown drive a few yards away from him. There was a clank of metal as the stand was lowered, and then a sound of footsteps which seemed to be coming straight towards him.

“Come along,” said von Rasberg irritably, “every second we spend here is fraught with danger.”

“I was detained,” replied a voice, which in some vaguely distant way seemed curiously familiar. For perhaps a second Rex actually lay, face downwards, between the two men, and he flinched instinctively, half-expecting to feel the crashing blow that would accompany discovery. He breathed again as the footsteps receded, and the sound of the window being closed above him reached his ears.

He heard a door slam somewhere not far away and he rose again as silently as a shadow and placed his eye to the slit. The three men were facing the door expectantly. It opened and Rex eagerly looked at the face of the newcomer.

For how long he remained rooted to the spot, staring in dumb stupefaction, he could never afterwards say; his brain literally reeled from a shock which seemed to paralyse his limbs. His lips went bone dry and the skin of his face seemed to tighten like elastic. Of all the people in France, the last he expected to see at that sinister rendezvous was the man at whom he was now staring in horror-stricken amazement. It was Major Trevor.

For a full minute the earth seemed to rock beneath his feet, and then, as he recovered himself by a supreme effort of will, a thousand thoughts rushed through his brain at once and he struggled to muster them into intelligible order.

With this stunning revelation everything was changed, and he tried to see the new position in its correct perspective. Good God! First Fairfax and now Trevor, of all people, he thought. No wonder information was leaking. Leaking! It must have been literally pouring out. Major Trevor was taking a bulky package out of the breast pocket of his trench-coat and Rex watched him as if fascinated.

“They are now complete,” announced the Major, speaking in German. “These maps show how the dispositions of the troops on this sector will appear on the first day of the big offensive. I’ve had a job to complete them, but there they are and I’m glad it’s done. I hope things will be a bit easier after this.”

At his next words Rex grew rigid with horror and rage.

“What have you done with those brats—Lovell and Fraser?” sneered Major Trevor with a sardonic smile.

“Done with them? Nothing—yet,” replied von Rasberg. “We thought they had got away this afternoon, but their engine let them down and they had to come back.”

“Well, von Hartzmann can do what he likes with them now. I’ve finished with them,” announced the Major.

You foul, treacherous hound, thought Rex, writhing with suppressed fury.

“I think,” went on the Major, “that this scheme of mine was one of the neatest I’ve ever put across. When I blundered over the affair of the tunnel——”

“Yes, how did that happen?” asked von Rasberg with interest.

The Major made a deprecating gesture. “I sent those two half-baked young fools on the job—I had to do something or the General would have wondered why. I was told to send somebody to do it and he would have done if I hadn’t. The long and short of it was I sent those two as you know, but I took every reasonable precaution to make sure they failed. I told them to land on field 117, which I knew was wired, and then gave them a charge with faulty detonators which I fixed myself. What must they do but first of all re-set the charge and then land on a field of their own choice. When I heard they had succeeded, I nearly threw a fit. It was a case of fools for luck, if you like. Von Hartzmann, of course, was livid about it, so in order to appease him, I sent them over to our place at Lille with a letter saying who they were and that they had better be put out of the way. The fools there let them slip through their fingers. Then they got on the trail of Fairfax. They think they are watching him now, but, of course, Fairfax is watching them.

“I think I started a good scheme when I got them flying over in that Hannoverana; they little knew I was making carrier pigeons of them. I had a slot put inside the fuselage and von Henkel or Hartzmann just collected my messages while they were drinking beer in the mess. Simple, wasn’t it? There they were, working hard to find out who was carrying the information which they themselves were carrying. I flatter myself that they’d hardly be likely to suspect themselves!”

The Major laughed at the grim humour of the situation.

You clever devil, gasped Rex aghast. You clever, cunning swine. The knowledge that he and Tony had been used as enemy agents appalled him, and he listened breathlessly to the story of betrayal.

“They were rather clever to spot Fairfax,” went on the Major, and again Rex struggled to get the situation correctly balanced in his mind. That Fairfax was a German spy was no news to him, and he now understood the Major’s attitude when he had broached the subject to him. The knowledge that the Germans had known about them all along filled him with a sense of bitter disappointment; no wonder things had been easy, and all the time they thought they were being clever. Rex squirmed with a burning resentment at the thought of how the Germans must have laughed at them—what fools they had made of themselves. He bit his lip until it bled in the fury of his bitter hatred against the man who had made dupes of them.

“One of them flew me over here to-night,” announced von Rasberg.

“What!”

Major Trevor spun round as if he had been shot. “Do you mean he brought you here?”

“Yes.”

“Why in the name of Heaven——”

“Wait a minute, don’t worry, the Chief is no fool. Von Henkel went sick this afternoon and it was the Colonel’s idea. It was more than that, it was inspiration. Who could be better than Lovell, or Wistmann, as he calls himself? In the first place, he knows the country better than any of our pilots, and if we ran into trouble—if the guns got us, or we crashed—we should lose one man instead of two.”

“But suppose he bolts while he is here?”

“What! And leave Fraser in Germany to be shot as a spy? Not likely. Do you suppose we had not thought of that?”

The Major nodded. “Yes, I see that,” he said. “It was a clever scheme, but I don’t like the idea of him being so close.”

“Fear not, my friend,” exclaimed von Rasberg impatiently, “Max is outside keeping an eye on him, anyway; he won’t let him leave the machine.”

“All right, but the sooner they are both under the ground the better I shall be pleased. Let us have no more of this foolery; they know too much already. Well, there are the plans; I must go now.”

“And so must I,” said von Rasberg rising and placing the plans in his pocket.

Rex waited for no more. He dropped on all fours and crawled quickly away from the château until he was round the corner of the outbuildings, when he broke into a run towards the machine. For a moment he was tempted to rush off to Wing Headquarters and have the traitorous Major arrested forthwith, but that would mean leaving Tony to his fate. Moreover, the plans of the British advance would then inevitably fall into German hands, and that had to be prevented at all costs. He next thought of striking von Rasberg down as he rejoined the machine, but that might sound the alarm to the other spies and he had no intention of allowing the Major to escape if he could possibly prevent it. No, he would have to think of something else.

A few moments later, when von Rasberg joined him, he was sitting, apparently dozing, in his seat. The Hauptmann looked around suspiciously. “Has no one been here?” he asked.

“Yes,” replied Rex, “Max—he didn’t tell me his other name—has been talking to me ever since you went; he’s just gone off over there,” he added, pointing in the opposite direction to the hedge under which the German was lying bound and gagged.

“I see,” said von Rasberg, “well, let us be getting away.”

They swung the machine round to give it the longest possible run, for there was no wind, and the big black-crossed machine roared up into the night.

An enquiring searchlight beam flickered up out of the darkness below, but Rex slipped down on his wing away from it. Another and another took up the chase, and archie began to stab the darkness with its orange and red flashes. Rex paid little attention to it for he was engrossed in his thoughts. To get the plans and destroy them must be his first action; but how? That was the question. Obviously he could not get them in the air and it would be too late when he landed at Varne; he would, therefore, have to make an intermediate landing, he decided. He remembered the field on which he and Tony had landed on their first expedition and he nosed the machine round almost imperceptibly on a course that would bring them to it.

With his left hand he groped for the ignition control and very slowly began to draw it back. The engine changed its note at once and a long tongue of flame licked out of the exhaust. Von Rasberg leaned over. “What’s wrong?” he bawled in Rex’s ear. The pilot shook his head and pretended to juggle with the throttle, but he retarded the spark still more until the vibrant roar of the engine became an intermittent splutter. Suddenly such a burst of flame leapt from the exhaust as the unexploded gas rushed through the red-hot pipe that he himself was startled.

“Go down!” yelled von Rasberg, now thoroughly alarmed, and Rex, throttling back, began a long glide towards the earth, leaning over the side of his cockpit as if searching for a suitable field. He turned, and beckoning to von Rasberg, pointed as if satisfied at the field upon which he had determined to land some minutes ago, and then glided in to a rather bumpy landing.

“It’s that damned magneto,” he growled after he had switched off the engine. “The brushes of these new magnetos have a nasty habit of sticking, but I’ll soon put it right. Have you got a torch?” he asked von Rasberg.

“Yes.”

“Well, perhaps you wouldn’t mind coming and showing me a light?”

Cursing luridly von Rasberg climbed out of his cockpit and walked round the wing to where Rex was unbolting the engine cowling with his spanner.

“Hello, I didn’t feel that lump of archie hit us,” said Rex, pointing to the fuselage at the junction of an undercarriage strut. “Just hold it a minute, will you?”

“Hold what?” asked von Rasberg, bending down to look at the strut.

“This,” said Rex, and brought the heavy spanner down with a thud on the back of the German’s head.

Von Rasberg pitched forward on to his face, and for the second time within an hour an unconscious man lay at Rex’s feet. He felt no compunction about the blow; von Rasberg would, he knew, have watched him shot without a quiver of an eyelid. The situation was one where desperate measures were needed and he was prepared to enforce them.

He dropped to his knees beside the inert form, unbuttoned the leather flying-coat and took the plans from the German’s pocket. What to do with them now he had them he did not know. To take them with him on his next desperate mission would be the act of a madman, he reflected. The packet was a bulky one and the paper tough and tightly packed; it would take some time to tear it up, and in any case, tearing was an unsatisfactory method of disposing of papers of such importance. It might even take some time to burn them. Suddenly he had an idea and he swung himself up on the lower plane and quickly unscrewed the draining tap of his gravity tank. A stream of petrol gushed out and he held the papers in it until they were thoroughly soaked.

What about von Rasberg? How could he dispose of him? That was a problem he could not solve. Alive, he was a danger, there was no doubt of that, but he shrank from killing an unconscious man, although he was in no doubt as to what the German would do had the situation been reversed. He had no means of tying him up, for his belt and muffler had already been used for a similar purpose. Well, he would have to leave him and take his chance, that was all.

Rex climbed back in his cockpit and taxied to the far end of the field into position for taking off. He scrambled out again, threw the petrol-soaked papers into the hedge, and then flung a lighted match on to them. The papers instantly burst into flames with a blaze of light that startled him; quickly he regained his cockpit and with one hand on the throttle ready for instant action, watched the small but furious conflagration. Satisfied at last that they were consumed beyond hope of recovery, he opened the throttle and soared up into the still night air. Glancing over the side as he swung round in the direction of Varne he could still see the glowing mass where the plans of the British advance were being charred to cinders in the terrific heat of the blazing petrol.

“Well, now for it,” he muttered grimly as, a few minutes later, he planed down on to the German aerodrome.

A little group of mechanics moved towards him in the darkness as he taxied in, and after telling them to stand by the machine in case he needed it again, he strode down the tarmac in the direction of the officers’ quarters, where he changed back into his German uniform before entering the mess.

In the corridor which led to the mess he paused in his stride and caught his breath sharply. Outside the mess door, standing “at ease,” was a Sergeant and two soldiers; the light gleamed on their fixed bayonets. Rex only paused for an instant and then, with a casual acknowledgment of their salute, he passed between them and opened the door.

Through a haze of tobacco smoke he saw some twelve or fourteen officers seated round the long table where they had evidently just finished dinner, for several wine bottles were prominent. At the end of the table nearest to him sat Colonel von Hartzmann; at the opposite end was Fairfax. Among the others Rex recognised Tony, von Henkel—who had evidently recovered from his influenza—and several other officers of the squadron. All eyes were on him as he walked across the room, rang the bell for the mess waiter, ordered some food, and seated himself at a vacant place at the table next to Tony.

A LITTLE GROUP OF MECHANICS MOVED TOWARDS HIM IN THE DARKNESS AS HE TAXIED IN

His first act must be, if possible, to warn him of the true state of affairs. He waited until the conversation was resumed and then he turned, and looking Tony in the eyes said in a normal voice, “Well, old boy, what have you been doing to kill time?” and then, dropping his voice to a mere whisper, he added, “They know who we are; keep your head; machine is on tarmac.”

The mess waiter entered and placed a plate of food before him, and although in his present condition the sight of food nearly sickened him, he proceeded to eat it, passing casual remarks about the weather and anything that occurred to him. It did not take him long to perceive that the attitude of the officers present had changed since last he saw them. The atmosphere of the room was charged with a tense expectancy that could be felt; he remembered the guard mounted outside the door and knew the reason. Their time had come. One advantage only he held; he knew that they knew Tony and himself in their true colours, but what they did not know was that he, Rex, was fully aware of it. He was ready for the Colonel’s question when it came, for his eyes had wandered frequently to the door.

“Where is your passenger?” asked von Hartzmann.

“He was not ready to come,” replied Rex casually without looking up, and helping himself to more sausage. “He came back in a towering rage to where I was waiting by the machine and said things had not worked out according to plan, and he might have to wait four or five hours. He said he thought the delay might make you anxious so I had better come back here, report the position to you, and then go back and fetch him at about 2 a.m.”

He hoped that his story would be believed and that he would be able to find some means or other of getting Tony into the back seat of his machine before the truth was discovered. He reached for another slice of the coarse German bread with a sang froid he did not feel, for in the hush that had followed his words he could feel the Colonel’s steely eyes boring into his brain.

“I see,” said von Hartzmann with ominous calm, and again a ghastly silence fell upon the room.

“What’s up with you all?” asked Rex, looking around with a grin. “Are you expecting a raid, or have you all caught von Henkel’s influenza? How are you, by the way?” he smiled, looking up into von Henkel’s scowling face.

The German made no reply.

“Pretty bad, I see,” went on Rex, answering his own question. A telephone bell rang shrilly in the distance and a moment later an orderly entered.

“Colonel von Hartzmann wanted on the telephone, please,” he called loudly.

Now Fate has ordained that in moments of great anxiety certain people are gifted with a perception so acute that it almost amounts to second sight, and as the telephone bell rang Rex was as certain of the cause as if he could see the caller at the other end of the line. He knew that von Rasberg had either been found, or had recovered from the blow and made his way to assistance, and was now ringing Colonel von Hartzmann, his Chief.

It did not surprise him, therefore, that when the Colonel returned to the room his face was white and set in a mask of grim Teutonic hate. His lips were pressed into a thin, straight line and his eyes flashed with a rage that he was evidently finding difficult to control; the eyes were turned on Rex, and the pilot felt a shiver run down his spine as his own eyes met the baleful gleam in the other’s. The Colonel stopped for a moment beside his own chair, picked up his wine glass and took a sip, slowly and reflectively, as if deciding on a course of action, and then walked round the table until he stood at Rex’s elbow.

“What have you done with those papers?” he asked slowly and deliberately.

Every word fell like a drop of ice-cold water on Rex’s heart.

“Papers—what papers?” he asked, looking up.

“You know what papers I mean—spy!” snarled the Colonel, and dashed the contents of his glass into Rex’s face.

There was a deadly silence in which Rex picked up a table napkin and mopped the liquid from his eyes.

“Don’t move, anybody!”

The words, low but vibrant, cut the silence like a whip lash. Nobody moved, and Rex, taking in the group with a quick sweep of his eyes, saw that Fairfax was leaning slightly forward; above the edge of the table in front of him were two little round black holes, the wicked-looking muzzles of a pair of automatics.

“Von Hartzmann,” went on Fairfax crisply, every word distinct, “I warn you that if any man in this room moves as much as a muscle, I will shoot you dead. I must also warn every other gentleman present that, although a call for assistance might result in tragic consequences for certain members of this party, the result will be equally tragic for the man who makes the sound. I need hardly tell you that in the circumstances I shall not hesitate to shoot.”

Rex, fighting to get a grip on his reeling senses, felt Tony’s hand clutch his arm like a vice.

“Lovell, Fraser, listen! Do exactly what I tell you,” went on Fairfax. “Go to the door and dismiss the guard. Tell them the Colonel is not ready, they are to return in half an hour. Fetch your machine and taxi down here until you are exactly opposite this door. Go.”

Mechanically the two boys rose to their feet. The Colonel’s hand started to move, but it stopped abruptly as Fairfax’s fingers tightened perceptibly on the triggers of his guns. Like a man in a dream Rex walked to the door with Tony at his heels. He opened it and stepped out. The Sergeant sprang to attention.

“You may dismiss,” said Rex curtly. “You will not be required for half an hour. Return then.”

The Sergeant saluted; there was a sharp word of command and the file marched noisily down the corridor and out into the night. Rex, mentally thanking Providence for the blind obedience to commissioned rank which is ingrained in every German soldier, hurried towards the sheds. The Rumpler was still standing where he had left it. They sprang into their seats, a mechanic ran to the propeller, and an instant later the engine started its powerful song. The pilot waved away the chocks and taxied quickly towards the mess; as he reached it he thrust the throttle forward and back quickly, filling the air with a sudden volume of sound as the noise of the engine rose to a quick crescendo and died away again.

Inside the room, Fairfax was standing with his back to the door, a queer smile on his face and his gun still covering the group at the table. With a quick movement he thrust one of the guns into his pocket, took the key out of the keyhole, opened the door and stepped backwards through it. Von Hartzmann sprang forward with a curse; a streak of flame leapt from the gun in Fairfax’s hand; the German spun round, and then crashed forward on to his face.

As Fairfax closed and locked the door behind him pandemonium broke loose in the room, but without waiting to see any more he ran like a deer towards the waiting machine. “Off you go,” he snapped, and flung himself at full length on the lower plane, near the fuselage, hands gripping the leading edge.

Rex shoved the throttle open and the Rumpler roared away, tail up, across the turf. The tension on the joystick increased as the machine gathered flying speed and Rex eased it back with wild exultation in his heart. They were off! He held the machine on her course until the altimeter needle showed a thousand feet, and then he banked round gently in the direction of the lines. Leaning out, he could see Fairfax’s dark figure where it crouched close against the fuselage; it was hardly a comfortable position, but within half an hour they would be safely over the British lines.

A searchlight beam stabbed the darkness ahead and whoof! whoof! whoof! flashed the archie-bursts. Rex was expecting it; he knew that every battery between Varne and the lines would be warned of their escape and would be on the lookout for them. Whoof!—bang! Whoof!—bang! crashed the shells, the distant bursts glowing dull crimson and the near ones a vivid scarlet orange. Rex used every wile he knew to throw the gunners off their mark, cutting off his engine from time to time and sideslipping away when the bursts came too close.

Whang-g-g-g! Something struck the machine with a crash that made it quiver from prop. boss to tailskid. The engine spluttered and a glance at a dial on his instrument-board showed Rex the cause of the trouble. The pressure in his main petrol tank had dropped to zero; a piece of shrapnel had evidently punctured the tank. He switched over to his gravity tank and the engine picked up again, but Rex’s heart had turned to lead, for he knew that there could not be more than ten minutes’ petrol left in that tank—and that was not sufficient to take him to the lines. He bitterly regretted using the precious fluid in order to burn the plans he had taken from von Rasberg, but he did not reproach himself, for the circumstances could not have been foreseen. He knew that a landing was inevitable and he racked his brain to try and remember a suitable field where he could land, and where, by some means or other, they might be able to get enough petrol to continue their journey. He did not wish to take any chances by landing in an unknown field, which, too late, might prove to hold obstructions and cause them to crash.

The nearest really good landing-ground that he could remember lay a few miles to the north. He had studied the map carefully and knew the country around, and he could not recall seeing any camps or buildings near the field he had in mind. Accordingly he switched off his engine and began a long glide towards it. Archie was still hammering away, but the gunners soon lost him without the sound of the engine to guide them. The fact that they were wearing German uniforms was now likely to be a valuable asset, reflected Rex, and they should experience no great difficulty in getting petrol—even if it meant stopping a car on the road. His spirits were, therefore, by no means cast down as he glided gently over the hedge that bordered the field. What happened next occurred too quickly for him to think, much less to act. Without warning the darkness was turned into broad daylight as a floodlight blazed out from a corner of the field. He heard the sound of many voices shouting, and he thrust the throttle open again, but it was too late, his wheels were already on the ground. Something seemed to catch the machine and it stopped dead, flinging him forward violently against his instrument-board. Automatically he switched off the spark. There was a deafening crash of breaking wood and tearing fabric as the Rumpler pitched up on to its nose and then somersaulted. His next conscious recollection was struggling to get out of the wreck, calling frantically to the others. He knew what had happened; he had struck a pilot trap; a field that had been wired in every direction to trip up hostile machines who were seeking to land on special missions.

Figures were running towards them from every direction. “Are you all right, Tony?” called Rex as he struggled to his feet and stood swaying in a blaze of light. “Where’s Fairfax?”

“Here I am,” replied Fairfax, crawling out from under a wing. “I knew about this field and tried to warn you, but I couldn’t get to you.”

A trickle of blood was running down the side of his face, and he dabbed at it unconcernedly with his handkerchief. “Well,” he went on, “we’re in a mess, but don’t lose your heads. I’ve been in worse holes than this and got out of them. Leave the talking to me.”

“What the devil are you doing,” roared an irate voice, “don’t you read orders? Don’t you know that landing on this field is forbidden?”

“Landing?” said Fairfax, grinning, to the German Leutnant who had spoken. “Do you call this landing?” he went on, pointing to the crash with grim humour. “Donnervetter! We had no choice when the engine packed up on us.”

“What were three of you doing in that machine?” asked the Leutnant suspiciously.

“Well, we might as well make a clean breast of it,” answered Fairfax reluctantly. “You look a good sport, so I hope you’ll say nothing about three people being in a two-seater—I’ll see you lose nothing by it.”

The Leutnant came closer and stiffened to attention when he saw that Fairfax wore the uniform of a Hauptmann.

“To tell the truth,” went on Fairfax, “we’ve been to a party in Lille. We couldn’t get road transport so we went the only other way we could—we flew; and now on the way back that cursed engine has let us down. Just my luck,” he concluded plaintively.

“Are you hurt?” asked the German anxiously with a change of tone, flattered by the senior officer’s friendly attitude.

“Oh, it’s nothing,” replied Fairfax, “only a scratch.”

“Well, come and have a drink and I’ll see what I can do,” smiled the Leutnant. “By the way, where are you bound for?”

“Varne,” answered Fairfax briefly.

“All right, I’ll see you are not late back.”

“For goodness’ sake don’t ring up the squadron,” cried Fairfax in real alarm. “Let us get back and tell our tale first. The C.O. can confirm it with you afterwards. You saw what happened. The engine cut out, and in the darkness and anxiety of the moment we forgot that this field was out of bounds.”

The Leutnant smiled. “Well,” he said, “as long as it doesn’t get me into trouble, I don’t mind. You can borrow my car and chauffeur to get home.”

They made their way through the excited troops to a corner of the field where a small, carefully camouflaged hut stood under the trees. The Leutnant gave a sharp order and a moment or two later an old four-seater Benz car trundled along the road to where they stood. They opened a bottle of beer with the friendly officer—it would have been difficult to refuse—and then took their places in the waiting car, Fairfax sitting next to the driver; and with a parting wave set off down the road.

“My word, it is chilly to-night,” growled Fairfax a few minutes later, groping in his hip pocket. He took out a flask, unscrewed the top, and placed the opening to his lips. “Sorry to fetch you out so late at night,” he apologised to the driver, “—here, take a pull of this, it will warm you up.”

The driver, with the ever-present German willingness to drink, stopped the car and accepted the proffered flask with a grunt of thanks.

“Ah,” he gasped, smacking his lips, “that’s great stuff. Got some kick in it, that has. It isn’t often that we poor devils get—a chance—hic—get—a kick—Gott in Himmel——” his voice trailed away to nothingness and he sank back limply in his seat. Fairfax rose calmly to his feet, seized the man by the collar, hauled him out into the road, and then carried him behind the hedge out of sight of any passers-by.

“He’ll have a difficult story to tell in the morning, I’m afraid,” he said coolly as he took his place at the driver’s seat.

“What on earth did you give him?” gasped Tony.

“Only a little drop of my own special brew,” grinned Fairfax. “It’s part of my equipment; I’ve often found it useful.”

“But why didn’t it affect you like that?” asked Rex in surprise.

“Me!” laughed Fairfax. “Good Lord, I didn’t drink any. I only pretended. That stuff is only for my special friends.”

“I see. Well, where are we going now?” asked Rex, changing the subject abruptly.

“Falconfeld,” replied Fairfax shortly. “You’d better come over here where I can talk to you.”

Rex climbed over into the front seat beside the new driver; Fairfax slipped in the clutch and they rattled noisily down the road.

“Before we go any farther, hadn’t we better put our cards on the table?” asked Rex.

“No,” replied Fairfax. “You know the old saying in our profession? ‘When you are at work, even if you meet your mother, you do not recognise her.’ You have no cards to show, anyway,” he went on. “I know them all.”

“The devil you do!” said Rex coldly. “Who are you, anyway?”

“You know,” grinned Fairfax. “Hauptmann Baron Gustav von Karnhofen—and the cleverest secret service agent in the German corps,” he added glibly.

Rex shook his head. “You may be,” he said slowly, “but you are working for our side or you wouldn’t have acted as you did to-night.”

“You’re right,” admitted Fairfax. “We’d better understand each other on that point. As a matter of fact, if I knew my job I should just have stood by and watched you shot, because by helping you I’ve exposed myself, and lost a position which has taken many years to acquire. I’m in as bad a fix as you are now and I’ve got to get out of it; unfortunately my work is not complete.”

“If you were waiting to short-circuit the plans of the British advance, you needn’t worry,” said Rex tersely.

“Why—how?”

“I’ve burnt ’em.”

“Good God! You don’t say so,” gasped Fairfax.

“I thought you knew all my cards,” smiled Rex, and then with a change of tone. “You don’t, Fairfax, not half of them. I’m going to play one now. I don’t like doing it, but I’ve got to in case you get back over the lines and we don’t. I’ve got to take a chance that you’re on the level.”

“What is it?” said Fairfax shortly.

“The name of the man who is at the head of the group of agents working behind our lines,” answered Rex crisply, watching the other’s face closely.

Fairfax risked a spill as he stared at Rex in amazement. “You know that, eh?” he muttered through his teeth.

“I do.”

“What is it?”

“Trevor. Major C. L. Trevor of 91st Wing Headquarters, to be more precise. How do you like the look of that card?”

The car pulled up with a sudden grinding of brakes and Fairfax stared at Rex in wide-eyed astonishment.

“If you get back and we don’t, you’d better get him,” went on Rex. “If he isn’t at home, I’ll tell you where you can find him. Make a dart at the Château Neuf on the Amiens road; I fancy you’ll find enough proofs there to hang him ten times over. That’s another card out of the pack you may not have seen,” he added with a grin. “And now perhaps you’ll tell me why we’re going to Falconfeld?”

“Because my S.E.5 is there,” replied Fairfax quietly, “and I reckon that card’s a trump,” he smiled, starting the car again.

Rex stared. “This game is too fast for me,” he confessed. “If ever I get back home, I’ll be satisfied with plain ordinary dog-fights in future,” he murmured sorrowfully. “Well, what about the S.E.?—we can’t all three get in it.”

“You will fly the S.E. back—if we can get it.”

“What do you mean—if we can get it?”

“Falconfeld is a German aerodrome. They have probably been warned of our escape.”

“And why do you suggest that I fly it, if we do get it?” enquired Rex.

“Because you can fly the Bristol, which is now at Neuville, better than I can. It would be safer. You’ve got to slip back, get the Bristol, and then come back here and pick us up. Fraser and I could just squeeze into the back seat; and it’s got to be done before daylight, don’t forget.”

“Where shall I pick you up?”

“Two miles due west of Falconfeld there is a large triangular-shaped wood. The apex points north, and it makes a good landmark. Just by the apex you will see a big field, which I happen to know is not wired. We shall hide in the wood after you’ve gone and then watch the field until you come back.”

“Well, let’s see about getting the S.E.,” grunted Rex.

Fairfax brought the car to a halt in the silent roadway. “The hangars are on the side of this road about a quarter of a mile ahead,” he said. “And the other side of this hedge, on our left, is actually the aerodrome. I think this is our best plan. We will get over the hedge here and walk quietly along to the shed where I left the S.E. If nobody is about, we’ll pull her right up to this end of the aerodrome before we start her up. If anybody wants to know what we are doing, we shall soon know whether they have been warned about us or not. If they have, well, there may be a scrap. If they haven’t there should be no difficulty; they are used to my queer comings and goings. If you get off, make for Neuville and get back to the wood as fast as you can. Is that all clear?”

Rex nodded.

“Come on then, this way,” muttered Fairfax, forcing his way through the hedge. “We must keep as far away from the squadron buildings as possible or the Headquarters guard will see us and we must avoid that if we can.”

For some time they walked in silence across the dew-soaked grass, and then Fairfax laid a restraining hand on Rex’s arm. “Here we are, down this hedge,” he said, leading the way as one perfectly familiar with his surroundings. A dark mass loomed up in the darkness ahead. “This is a small hangar that has been set aside for my use,” he whispered. “Hark!”

The silence was intense. Only the far-off sound of an engine whistling and the distant rumble of the guns along the front reached their ears. Stealthily they crept to the front of the hangar and stared with straining eyes into the darkness along the tarmac. Tony’s heart was thumping painfully and he was glad when Fairfax, noiseless as a cat, led them both through a fold in the front of the canvas shed. Inside, Fairfax again paused to listen. A match flared in the darkness and was held above his head as he looked suspiciously around. In the dim light they could just make out the shape of the S.E.5.

“Good,” he muttered under his breath. “Pull back the doors—don’t make more noise than you can help.” He lifted the S.E.’s tail and began to drag the machine backwards towards the entrance, which was, of course, the easiest way to move it.

“What’s that?” asked Rex suddenly, and again they all stiffened into attitudes of tense expectation. Some distance away, but rapidly coming nearer, was the unmistakable whoof! whoof! whoof! of archie. Rex groped his way through the canvas door and peered out; a few miles away the air was full of dancing specks of fire, and a dozen searchlight beams probed the sky with their silent fingers. “They are coming this way!” he cried in a low voice. “Jumping snakes! I believe they are coming here; it’s a raid!”

The hum of the aero engines was now plainly audible, and the silent aerodrome suddenly broke into unbelievable turmoil. Doors slammed. Orders were shouted and voices yelled back. There was a sound of running footsteps along the tarmac and all the noises of a sudden panic. Outside the squadron office a machine-gun broke into a series of short, stuttering bursts, and a stream of tracer bullets winged their way into the sky. The hum above was drowned in a whining shriek that rose swiftly to a shrill crescendo.

“Bombs!” yelled Fairfax, and together they dashed for the hedge.

There was a blaze of flame that seemed to reach to heaven as the first bomb landed not a hundred yards away, and the rush of air that followed the roar of the explosion swept Rex off his feet. Another pillar of fire leapt skywards, temporarily blinding him. “Tony! Tony—where are you?” he shouted wildly.

“Here!” cried a voice near at hand.

“Let’s get out of this!” yelled Rex, trying to force his way through the hedge. “There’s a dozen bombers up there and they’ve only just begun.”

The noise was indescribable. The shriek of falling bombs, the stunning crash of explosion after explosion, and the incessant rattle of machine-guns seemed to make the earth rock. Anti-aircraft guns and field guns joined in the general uproar, and the sky was full of stabbing flame and the white criss-cross lines of tracer bullets. Yells and groans mingled with the noise of falling debris; low overhead roared the engines of the heavy bombers. A thundering detonation not fifty yards away seemed to lift half the tarmac above the sheds and Rex saw the S.E.5 hangar blaze up like a petrol-soaked rag. In the middle of the leaping flames stood the machine in which they had hoped to escape, and even as Rex watched it he saw the petrol tank explode in a fountain of flame.

“Come on—come on, let’s get away!” he cried again incoherently. “God! What a row. Where’s Fairfax?”

“I haven’t seen him!” screamed Tony, gasping out a mouthful of acrid smoke.

“Fairfax!—Fairfax!” shouted Rex, but the sound of his voice was smothered in the roar of the raging inferno, for the hangars were now all ablaze and cast a vivid orange glow over the scene of carnage and destruction. Prone figures lay in grotesque positions near the blazing ruins. Rex saw a German officer trying to drag a machine out of the flames. A Fokker D.VII raced across the aerodrome like a living streak of fire and then soared into the heavens like a comet. Another pilot was standing up in the cockpit of an Albatros, yelling for someone to start his engine. He sprang to the ground and ran round to his propeller; a bomb caught the machine amidships and it vanished in a cloud of flying fragments, the pieces falling like a shower of fiery rain.

Sobbing and gasping for breath Rex dragged Tony into the next field. “Come on,” he choked, “the place will be alive with troops in a minute. Why didn’t Fairfax stay with us?”

Blindly they ran on, stumbling and falling into the night. “Wait!” cried Rex at last, his breath coming in great gasps. “Where are we? Let’s get to the wood—Fairfax’s wood—two miles to the west, he said—he’ll make for there if he isn’t hit.”

A Handley Page, evidently one of the raiders, roared past just over their heads and Rex shook his fist at the pilot who, unconsciously, had helped to spoil their plans. They slowed down to a steady trot, crossing roads and fields as they kept their direction by the stars.

“This must be it,” said Rex at last, coming to a halt.

In front of them lay a sinister-looking wall of darkness. Rex’s surmise proved correct; it was the wood, or at least a wood, and they swung to the right towards the north end. They soon reached the point that Fairfax had described; it was still pitch dark. Rex looked at his luminous watch. “Four o’clock, eh?” he muttered. “Well, I don’t know about you, Tony, but I’m all in. I couldn’t make another mile if the whole blinking German army was on my heels. Let’s get in here and rest—we can’t do anything, anyway, until the morning and it’s not much use making plans until we know if Fairfax got away. I hope he has, because he may have a scheme, which is more than I’ve got. I’m too tired to think.”

Together they crawled into the undergrowth. Fortunately the place was fairly dry and there was plenty of bracken, which they plucked in armfuls and piled under a tree, the prickly nature of which revealed it to be a holly. They sank down on their primitive bed utterly worn out.

“Well, if this is special missions, you can have ’em,” growled Rex, and the next moment was fast asleep.

*      *      *      *      *

He was awakened by the sound of an aero engine low overhead. It was still dark, but a pale grey light in the east showed that the dawn was not far off. Raising himself on his elbow he listened intently.

“Tony!—Tony! Wake up,” he muttered in a low voice, shaking his still sleeping partner.

“What is it?” asked Tony sleepily, opening his eyes.

He was wideawake in a moment, his ear turned towards the sound of the now receding engine. “That’s no Mercedes,” he said excitedly; “that’s a Rolls-Royce, or I’ll eat my hat.”

“It certainly sounds like it,” said Rex, quivering with excitement, “but who on earth can it be? Poor old Fairfax hasn’t turned up, they must have got him. I’m sorry about that, I was just beginning to like him. Good Lord! That machine’s coming back again—I believe it’s going to land.”

The machine was very low now and a sudden “blipping” of the engine brought both of them to the edge of the wood at a run.

“That’s Fairfax, or I’m a Dutchman!” cried Tony. “He’s blipping his engine as a signal to us. He guessed we would come here. Hark!”

It was still too dark to see more than forty or fifty yards, but there was no doubt that the machine had landed, for Rex distinctly heard the wheels bump as they touched the ground.

“Stand fast a minute, Tony,” he said, catching hold of his companion, who was about to rush forward into the field. “I’m getting tired of falling into traps. How could it be Fairfax, unless—I know!” he cried in a flash of inspiration. “He must have got away in one of those Hun single-seaters when the raid started. He’s been over the lines and fetched the Bristol. Well, we’ll soon find out, but be ready to bolt.”

Cautiously, peering anxiously ahead, they strode out into the dim dawn twilight. An aeroplane loomed darkly in front of them and they ran forward with a faint cheer as they recognised the familiar outlines of the Bristol Fighter.

“Fairfax!” cried Rex excitedly. “How did you do it?”

A figure in flying-clothes was climbing out of the pilot’s seat.

“How did you manage it?” asked Rex again.

“Easily,” replied a voice in English as the figure turned and faced them and, with a sudden movement, pushed up his goggles to disclose the face of von Henkel, smiling evilly. In his hand gleamed the polished barrel of an automatic. “Don’t move, either of you,” he said. “Yes, it was easy,” he went on with a sneer, “you forgot I had a Bristol, too. There are very few fields about here big enough for a machine to land in, so it didn’t take me long to find you. We heard you were down within five minutes; the crash was heard for miles. Keep those hands up and do what you’re told; I’m in no mood to take any more chances with you. Make one false move and I’ll shoot. Now—where are those plans?”

“Where you won’t get ’em,” replied Rex grimly.

“I’ll give you ten seconds to make up your mind,” snarled von Henkel. “Tell me where the plans are and I’ll take you back for a fair trial.”

“I can imagine what your idea of a fair trial would be,” exclaimed Rex coldly.

“Refuse, and I’ll shoot you where you stand. I’ve no time to waste.”

“Bah!” sneered Rex. “You might as well know the truth and shoot us now as later on. I burnt those plans last night. Put that in your pipe and smoke it—and I hope it chokes you.”

“You burnt them, eh?” gritted von Henkel through his clenched teeth. “Then take this for a schweinhunt Englander.” He threw up the automatic.

There was a spurt of flame and a crashing report of a shot.

Von Henkel stared at the boys with wide-open eyes, an expression of curious surprise crept over his face. His arm drooped, his knees sagged, and he slumped forward on to the wet grass.

“I don’t know where you fellows would be without me,” said a well-known voice calmly.

Fairfax stood before them, a still smoking pistol in his hand.

“Where have you sprung from?” gasped Rex.

“Oh, I’ve been here an hour or more,” stated Fairfax casually. “I did some quick thinking when that raid started. When the S.E. blew up it looked as if now or never was the time to get hold of another machine, so I slipped across and jumped into that D.VII that was standing on the tarmac. I didn’t expect anybody would ask me where or why I was going, and I was quite right, they didn’t; the Handleys were giving them plenty to think about. I slipped over and fetched the Bristol, landed here an hour ago, and have been hunting high and low for you in that infernal wood ever since. I heard this machine land and came across to see what was going on, and it looks as if it was a good thing for you I did. You were all far too engrossed in the argument to notice me walk up behind the machine. But come on, don’t let’s stand talking here; that shot may have been heard; there’ll be plenty of time to talk later on. There is no need for three of us to pack into one machine now. You take Fraser back in this one, Lovell, and I’ll go back in the machine I came in. We’ll fly back together. It’s a bit thick down here, but it’s clear enough once you get above five hundred. Take off straight in front of you, you’ve plenty of room, and rendezvous over the wood at two thousand feet in three minutes.”

Rex was in the cockpit in a flash, Tony swinging up into the back seat. The Bristol moved forward as the engine burst into its rhythmic roar; the tail lifted, and they soared gracefully into the still morning air.

As Fairfax had said, it was clear overhead; they circled until he joined them and then, side by side, the two machines raced for the lines. Tony kept a vigilant lookout, but they were not molested, and the two pilots waved gaily to each other as the shell-torn earth of no-man’s-land swept below and behind. A moment later the British lines could be seen underneath. Rex turned with a broad grin on his face and stuck up his thumbs jubilantly. In less than ten minutes the two machines landed side by side at Maranique.

“And now for Trevor,” said Fairfax grimly, as they turned towards the mess. “You’d better come over to Divisional Headquarters and tell me all you know. It’s time we compared notes.”

The Brigadier to whom they told the story listened white-faced to the tale of treachery and betrayal.

“Very good, gentlemen,” he said at last, after a long pause, “this will, of course, have to be reported to the Commander-in-Chief. You can leave everything in our hands now, we’ll do the rest. I shall need you all at the court of enquiry, possibly before, but meantime you had better get some rest. Lovell and Fraser, go back to your unit and await my instructions. Fairfax, you’d better stay here for a bit in case the General wishes to ask any further questions.”

Rex felt that he had no sooner closed his eyes than he was awakened by the violent shaking of his batman.

“What’s the time?” he murmured drowsily.

“A Captain Fairfax is on the ’phone for you, sir, he says it is very urgent,” replied the ack-emma.

Rex leapt bolt upright as if he had been stung by a hornet. “Fairfax did you say?” he cried in astonishment.

“Yes, sir,” answered the orderly, “that was what he said his name was, sir.”

Without even waiting to put on a dressing-gown Rex dashed to the ’phone and put the receiver to his ear.

“Lovell here—is that you, Fairfax?” he called.

“Yes. Listen, Lovell,” came the reply, “I’m speaking from a field telephone near Château Neuf. The place has just been raided and we’ve scooped the pool except for the big fish. You know who I mean? Somehow or other he got through the cordon and pushed off in a D.H.4 before we could stop him. I don’t think he can fly himself, so he must have got a pilot with him. He has headed for the line, your way, about three minutes ago. I daren’t ring up the Service Squadrons to stop him or our people will be shooting each other down, that’s why I’ve rung you. You know where he’ll make for and the General says you can take any steps you like to prevent that machine reaching Germany,” he concluded.

“Right! I’m after him,” yelled Rex and slammed the receiver down with a crash that must have nearly deafened the man at the other end of the wire.

“Run like the devil to the sheds. Tell them to get my machine out and start her up. I’ll be there in two minutes. Run, man—run!” he shouted at his startled orderly, and then burst into Tony’s room like a whirlwind.

“Tony! Tony—come on, out of that!” he cried, pummelling the recumbent figure on the bed. “Trevor has escaped—he’s in a Four making for the line—jump to it, I’m on my way.” He stopped at his own room only long enough to snatch his flying-kit from the peg and pull it on over his pyjamas. Buckling his belt as he ran he sprinted down the tarmac towards the Bristol fighter which he could see already ticking over.

“Come on down, Smyth,” he yelled to the fitter who was sitting in the cockpit warming up the engine, and as the mechanic tumbled out of his seat Rex sprang into his place, fastened his safety belt, and thumbed the throttle impatiently.

Tony, looking ridiculous in his sheepskin boots and pyjamas, coat and helmet over his arm, came racing down the tarmac towards him. Rex opened the throttle to test his revs. while the mechanic clung like grim death to the tail to keep it from rising in the swirling slipstream.

Tony leapt nimbly into his place. “Look out!” yelled Rex to the mechanics and waved his arms above his head. Tony was pouring a stream of lead into the ground to test his guns. He struck his pilot lightly on the shoulder to show that he was ready, and then quickly pulled on his flying-kit. Before he had fastened his helmet the Bristol was in the air, climbing in wide circles for height. He pulled on his gauntlets, adjusted his goggles, and surveyed the sky doubtfully. There was a lot of broken cumulus cloud at about six thousand feet and he knew that it would form a ready-made hiding-place for another machine that was seeking to escape. In a few minutes they had reached the great white accumulations of moisture, and the pilot put his nose down for speed and then zoomed steeply through a hole to the blue sky above. He was just in time to see a D.H.4 disappear into a cloud about a mile away, heading for the German lines.

“There he goes!” yelled Rex, rocking his wings and pointing, and the round, stub nose of the Bristol swung round as he started in pursuit. He believed that he had an advantage over the other pilot in that he had not been seen, but he was not sure. In any case it was going to be difficult to keep the D.H.4 in sight. The cloud into which the Four had disappeared was too big to go round, at least it would mean making a wide detour, so he plunged boldly into it in the wake of the fugitive.

It was dull, cold and clammy inside the soaking wet fog, but he held on his way with a watchful eye on his instrument-board. The engine started racing and he knew that his nose was dropping. He pulled the stick back gently in an effort to check it, but the bubble in the centre of his bank-indicator began to swing from side to side in an alarming way; he made no effort to check it, for he knew from past experience that “bubble chasing” was a waste of time.

He burst into the sunlight with startling suddenness, and bringing the machine on even keel, peered ahead through his centre section in search of the other machine. He saw it almost at once, about half a mile ahead and slightly below him, evidently having lost some height in the cloud. A tall figure was standing in the back seat and Rex had no further doubt as to who it was.

Apparently the man had not seen them, for he was standing staring over his tail and had not moved since the Bristol appeared. Rex started to edge his way into the sun, but he was too late. He saw the gunner turn round, signal to his pilot, and then swing two Lewis guns round on their Scarff mounting. Rex put his nose down and rapidly overhauled the runaway. While he was still two hundred yards away he saw the tracer leap from the other’s guns and his lip curled in a sneer. Either he is scared stiff or he thinks this is just a casual machine and he is trying to scare us away, he mused. The pilot of the Four had put his nose down, too, and was racing full out for a mighty cloud-bank that towered up to high heaven straight ahead.

If he once reaches that he’ll stand a good chance of getting away, thought Rex and tilted his nose down a little steeper. The gunner in the other machine was shooting at him all the time, firing long bursts which would soon exhaust his ammunition if he kept it up. Ah! he has run to the end of his drum; now’s my chance, thought Rex, and he charged in with a double stream of lead pouring through his flashing propeller from the twin Vickers guns on the engine cowling. The pilot of the De Havilland machine lost his nerve under that deadly hail and swerved wildly. Rex’s dive carried him below and past his adversary, and as he zoomed up on the far side he heard Tony’s Lewis guns begin their staccato song. They were on the very edge of the cloud-bank and Rex turned just in time to see the other machine disappear into it in a steep dive. A huge V-shaped cleft split the clouds a short distance to his right and as he veered towards it he looked round at Tony and raised his eyebrows enquiringly. The gunner made a gesture of annoyance and turned his thumbs down; he had missed. “I think one of us must have hit him!” he bawled in Rex’s ear as they roared through the valley of cloud looking for an opening.

Rex had made no attempt to follow the other machine into the cloud, knowing quite well that such a course would be useless, and he was content to fly a parallel course through the cleft in the cloud-bank, hoping that the other machine would be in sight when they emerged on the other side. The roar of the engine and the whip of the propeller reverberated deafeningly from the towering walls of cloud on either side as they thundered along on the trail of the fleeing traitor. A great mass of mist projected into the narrow lane just ahead of them and as they flashed by it a wide patch of blue sky came into sight.

They had nearly reached it when the D.H.4 emerged from the cloud in a steep bank just below them, and Rex’s eyes were already seeking his gun sights when Tony struck him on the shoulder with a wild yell and pointed. Following the outstretched finger Rex gave a gasp and stiffened in his seat; a mixed circus of about twenty Albatrosses and Triplanes were dropping vertically out of the sky above them like vultures hastening to a kill. Rex swung the Bristol round in a lightning turn, and thrusting the stick forward, plunged back into the cloud. The Major would have to go. To attempt to continue the pursuit with so many enemy machines about would be suicidal. They burst out of the cloud again into the sunlight and as Rex snatched a swift glance around, a cry of startled surprise broke from his lips.

There was no need to point, for Tony’s eyes were already fixed on a scene which was to remain in their memory for ever. The luckless Four was roaring down towards the ground, a long plume of black smoke trailing out behind it; above and around it a cloud of triumphant black-crossed machines were following it down. Rex realised that unless they were fortunate, the Major’s fate was likely to be their own, for already the uppermost German scouts had seen them and were turning in their direction. He literally flung the Bristol back into the cloud and breathed a sigh of relief as they were once more swallowed up in the swirling mist. He kept his direction towards the lines as well as he could and when he again emerged from the cloud-bank he put his nose down in a steep dive and raced for home. He knew it was no use trying to outclimb the Triplanes, but there was a chance that they might hold their own with them in a dive. The thought of Major Trevor’s end brought a grim smile to his lips. What a curious trick of Fate it was, he thought, that he should have been sent to his death by the very people he had taken such risks to serve.

Rex knew what had happened; either the pilot of the D.H.4 had been unaware of the recognition signal, or had not had time to make it. It was possible that he had not even seen the circus above him until it was too late, and the flail of death was already shooting the machine to pieces about him.

Another towering cloud lay ahead, and as he reached it the circus burst out of the big cloud-bank behind him. He examined the ground closely and saw that they were still four or five miles over the lines. Against the inevitable head wind it would take them quite five minutes to reach safety; it was not long, but there was ample time for tragedy to overtake them. Almost anything could happen in five minutes.

Something did happen, something quite unexpected, but something which brought an Indian-like whoop from Tony’s lips. Rex looked back over his tail; the Fokkers were turning away. He raised his eyes and saw the reason; a big patrol of S.E.5’s had seen the unequal fight from high above and were roaring down to the rescue. The boot was now on the other foot and it was the Fokkers’ turn to fly for safety.

THE LUCKLESS “FOUR” WAS ROARING DOWN TOWARDS THE GROUND

As they raced across the lines Tony emptied drum after drum of ammunition into the enemy trenches below, and Rex breathed a sigh of relief as they passed over into the security of their own lines. Tony tapped him on the shoulder and grinning broadly raised both thumbs high in the air. Five minutes later they touched their wheels on the aerodrome at Maranique.

The first person they saw when they landed was Captain Fairfax and he waved a cheery greeting to them as the Bristol ran to a standstill on the tarmac. To think that we thought he was a spy, mused Rex as he switched off his engine. Well, Trevor at least told the truth when he said you could never tell who was friend and who was foe in the espionage game.

“What happened?” cried Fairfax excitedly as the boys clambered stiffly from their seats.

“He went down in flames about halfway between here and Varne,” replied Rex quietly.

“It is all fairly clear now,” said Rex as they settled themselves down in his room after a wash and a good meal, “but there are still one or two things I am a bit hazy about. I can see that Trevor had some difficult problems to face if he was to hold his job. For instance, he was told by the General to put someone on that tunnel job, and he sent us. Naturally he did his best to make sure that we failed, but both the traps he set misfired, and it must have shaken him to see us come back. We know that he got it in the neck for that from the other side. It is quite certain, too, that he thought you, Fairfax, were an agent working for Germany, and he got the wind up properly when he learned that we had spotted you. That was why he sent us to Lille—to get rid of us—but we slipped through his fingers again.

“Then he got a brainwave about making us carriers, and I must say that was pretty smart, particularly as he thought he could have us shot when we had served his purpose. But I still do not quite see where you fitted in. It looks as if you were a German spy, but actually working for the British.”

Fairfax nodded. “That’s about it,” he said. “It’s been done before and it’s still being done to-day.”

“It was you outside the window when Trevor was giving us instructions about the Lille show?” asked Rex.

“It was,” admitted Fairfax with a grin. “It’s funny, but I did not suspect Trevor even then. I turned up at the rendezvous to see that you didn’t get into trouble, but you got to the house faster than I expected.”

“We jumped a German lorry,” grinned Rex.

“And it looks as if you nearly jumped into the frying-pan as well,” said Fairfax seriously. “I was in a difficult position all the time because I dared not let you into my real identity. Why, you might have been German spies yourselves for all I knew; it doesn’t pay to trust anybody.”

“What about that day we held you up in the Boche hangar?” asked Rex. “You must have been sick.”

“I was; in fact, I was within an ace of telling you who I was. You see, I had some papers the German Higher Command had asked for and I had to deliver them or incur suspicion; needless to say, I had altered them so that they were really of no value. I had to produce the papers that day and I raced off after you in the S.E. determined to knock you down to get them back if necessary. I waited for you in Trevor’s office, but I saw at a glance that you hadn’t got them on you; it was a fairly bulky package, you remember? As you know, I got them out of the pocket of your flying-coat. It was a good thing I did, for had you shown those papers to Trevor, I should have been in a mess; he would have seen that they were useless and suspected me at once. It just shows how intricate the game becomes. There was Trevor, faced with the task of unravelling a spy system of which he was one of the prime agents! And there were you looking for the people who were carrying the messages and all the time you were carrying them yourself. Well, stranger things than that have happened in the records of espionage. These things are not altogether coincidence, you know, don’t get that idea; Trevor was probably working for years before the war to get into that very position ready for when war did break out; and I did the very same thing over the other side. With unlimited money and influence behind you it can be done. He knew, or rather thought, that I was working for his side. How he found out, I don’t know, and I don’t suppose I ever shall know. After the lesson of 1914, when every German spy in Great Britain was scooped up in one net through them being known to each other and having a common rendezvous, I thought the Wilhelmstrasse took care that agents were unknown to each other. Just see how strangely these things work out.

“I was with the General at H.Q. when he told Trevor to find the spy who was going to and from Germany, and all the time he thought it was me. I never suspected him. Why should I? I knew you suspected me; in fact, it was more than suspicion after you got my finger-prints so neatly. That was smart. I had taken all sorts of precautions, too. For instance, I told my assistant at H.Q. that if ever you rang me up he was to say I was there. I thought you might do that, and as a matter of fact you did.”

“Suppose I had insisted that I must speak to you,” said Rex.

“You didn’t, though,” grinned Fairfax. “You could have called my bluff had you dared to go far enough, but I didn’t expect you would, and it panned out as I anticipated. H.Q. were ready for you had you rolled up with a warrant demanding my arrest, for they were following your movements very closely.”

“Watching our movements!” cried Rex in amazement. “How the dickens could they do that?”

“I was telling them,” smiled Fairfax. “I had to report on what you were doing every day. They were a bit scared at first for fear you got yourselves into trouble and upset the whole apple-cart, but when they realised you were able to hold your own, they let you go on in the hope that you might strike something useful, as indeed you did. I can tell you that H.Q. is very pleased with you and I should think you will both get a decoration.”

“I couldn’t figure it out at all when you didn’t blow the gaff on us after we had held you up at Varne,” broke in Tony. “That got us absolutely stumped.”

“It put me in an awful hole,” replied Fairfax. “I was afraid that my failure to report you might lead you to suspect that I was working on your side. If you had once spotted that, it would only have needed a glance from you at the wrong moment to have sent me before a firing party. At the finish I had to step in, as you know. I had got to like you both and I couldn’t just stand by and watch you shot, as you certainly would have been by now. Strictly speaking, I had no right to butt in. I should have let you go to the wall because by exposing myself I have ruined most of my value to our side. I dare not go back openly now any more than you dare. It was a pity it came to a show-down. I hoped you were both going to get away in the afternoon when you were trying to collar that Rumpler. I had my eye on you.”

“We saw you had,” said Rex drily.

“It was tough luck you couldn’t manage it. It shook me to see you both crawl out of that machine after you had to force-land; it looked as if you were in a pretty mess.”

“Well, I shouldn’t have known about Trevor if it hadn’t have been for that,” said Rex grimly.

“Well, Hartzmann was a clever old devil, but he overreached himself by sending you on that special mission. He knew you would come back while he held Fraser; in fact, he had allowed for every possible emergency except one.”

“What was that?” asked Rex.

“Me,” answered Fairfax. “He failed to realise that there might be a flaw in his own cast-iron organisation. Everyone makes a boob sooner or later; that was his and it was his undoing. You can’t really blame him; he had to trust somebody. My hold-up in the mess afterwards was simpler than it looked, or sounded. I had the whole table covered, stone cold. It is an old trick. Everyone wanted to see me downed, but no one wanted to be the first man to die. I’ve got out of worse fixes than that.”

“I hope we shall never be in a worse one, anyway,” observed Rex grimly, “and I’ll thank you now for what you did. Maybe we shall have the opportunity of doing the same for you one day.”

“Bosh,” replied Fairfax; “people in my profession don’t look for thanks—we shouldn’t get ’em if we did. You would have done the same for me and as likely as not you’ll have the opportunity of proving it one day. Well, I think that’s cleared the air a bit. You’d better forget about the whole thing. My name is Fairfax of Divisional Headquarters. Forget everything else about me and never mention my name in any other capacity—walls have ears, you know.”

“Well, from what I have heard from Headquarters, and that isn’t much, I should imagine that neither of you is sorry to be back at the squadron again,” smiled Major Lukers to Rex and Tony as they reported for duty at their old squadron after a few days’ leave of absence, which they had spent “seeing the sights” in Paris.

Rex laughed. “Oh, I don’t know, sir; it was all very exciting and we have the satisfaction of knowing that we did some useful work for the Higher Authority,” he answered. “We shall have to be careful, though,” he added soberly. “The General wanted to send us home, out of the war for good. He warned us that we must never fall into the hands of the enemy or we shall have pretty short shift.”

“Naturally,” replied the Major seriously. “Even an officer who escapes from Germany in the ordinary way is liable to be shot as a spy if he is recaptured at a future date. They must hate you pretty thoroughly over there. Don’t go far over the line—that’s my advice; take things quietly for a week or two and give the pot that you must have stirred up a chance to simmer down.”

The telephone at his elbow rang its jangling summons, and as the Major picked up the receiver the boys turned to leave the room.

“Wait a moment,” called the Major; “this is Headquarters on the line—it may be something for you.”

They waited in the doorway while the C.O. continued his conversation.

“Yes, sir—I will, sir—certainly—I’ll send them along right away—good-bye, sir.” He hung up the receiver and eyed the two officers wistfully.

“It looks as if I’m going to lose you again,” he said with an anxious frown. “General Fellowes wants to see you both in his office as soon as possible. You can’t land there, so you had better go by road; take my Crossley.”

“Thanks, sir,” replied Rex, “we’ll report at once.”

The Major stared at the door thoughtfully for a full minute after they had gone, and then, with a gesture of helplessness, resumed his writing.

“What do you suppose he wants us for?” asked Tony as they sped along the road towards Divisional Headquarters.

“I don’t know,” replied Rex gravely, “but I’ve a feeling in my bones that something has happened. Did you notice the Major’s expression while the General was speaking to him?”

Tony nodded. “Yes,” he replied. “I’m afraid something is in the wind. I hope he doesn’t want us to go and land at Varne again, that’s all,” he muttered with a wry face.

“We shall hardly be likely to do that,” laughed Rex, “but here we are, we shall soon know all about it.”

“The General is expecting you,” announced the red-lapelled Staff Captain to whom they reported. “Stand fast a moment and I’ll see if he’s ready.”

He disappeared into a room leading off the corridor to reappear almost immediately and beckon them with his finger. “In you go,” he said.

“Sit down, gentlemen,” began the General. “I am very busy, so I must come to the point without preamble. First of all, I may tell you that the excellent work you have been doing for us lately has not been overlooked, but you will hear more about that through official channels in the near future. My next news is not so good; indeed, it is definitely bad.” The General paused and drummed on the desk before him with his fingers. “It concerns Captain Fairfax,” he added slowly.

Rex started and stiffened into an attitude of expectancy.

“Two days after the recent disturbing events with which you are fully acquainted,” went on the General, “it became very necessary for us to locate the exact whereabouts of the long-range gun the enemy is using against our rest-camps. It is hardly necessary for me to say that the mission was a very dangerous one and Captain Fairfax asked to be allowed to undertake it. I hesitated to permit it as he is such a marked man, but he was so desperately keen to go that I allowed myself to be persuaded into granting permission. He expected to be back within forty-eight hours; at the end of that time he was to keep an appointment with the pilot who took him over, and who was to bring him back. He failed to keep the appointment, and we know what that means. I was afraid that Fairfax had been apprehended by the enemy, but this morning I received a message which put a different complexion on things. The message was brought in by carrier pigeon and was written on paper which we are able to identify as that carried by Fairfax. The message is in code, but I will decipher it for you.”

The General took up a tiny slip of paper from the desk before him and read aloud.

“That is the pin point of the farmhouse, of course,” continued the General, looking up. “At the foot of the message is the number by which Fairfax is known to us. He also gives us the position of the gun. Well, gentlemen, that is how things stand and I am afraid he is in evil case. It would not be fair for me to ask a regular operative to go to his assistance because it would be irregular. We never do that. Now I believe the Captain recently ran a great risk to help you. I am not going to ask you to go and fetch him, because that, too, would be irregular, but in the circumstances, in fairness to you all, I—er—well——”

“Quite, sir. I understand,” broke in Rex.

“If anybody volunteered to go and fetch him, it is possible that I might sanction such a step,” continued the General, examining his pen reflectively.

“In that case I beg to apply for twenty-four hours’ leave of absence,” said Rex quickly.

“All right, fill in your forms at once and ask Major Lukers, with my compliments, to send them on to Wing by hand to-night. You may assume that your application is granted. Thank you very much. Good-bye—and the best of luck.”

The boys saluted and withdrew. They took their places in the waiting car and were almost back at Maranique before either of them spoke.

“Well,” said Rex at last, “the more I think about that message the less I like it.”

“I must say I’m not very keen on——”

“Oh, I don’t mind going over there,” interrupted Rex impatiently. “It isn’t that. There was something about the way that message was worded that didn’t ring true. It smells fishy to me.”

“Fishy?”

Rex nodded. “Fairfax is the last man on earth to send a message like that if I know anything about him. What did he say? ‘Wounded and in great danger.’ Danger, my eye. If Fairfax was in a mess, he’d see about getting out of it. The very last thing he would be likely to do would be to suggest that someone else should risk his life to get him out of it—for that’s what it amounts to. Do you suppose that if I was in a hole, I should expect Fairfax to come and stand a good chance of facing the firing party with me? Not on your life. Neither would he. He’s the sort of chap who relies on his own wits—not other people’s.”

“Well, what are you going to do about it?” asked Tony in alarm.

“I’m going over, of course.”

“But——”

“Never mind but; we can’t do less. One thing is certain, and that is that Fairfax has been nabbed or he would be back by now. Dash it all, we should never forgive ourselves if we heard that he had gone West behind the riding school at Lille, without either of us lifting a finger to help him. No! He took a big chance to get us out of the worst hole we are ever likely to be in—whatever he says about it—and I’m going to find him if I can.”

“When do we go?” asked Tony.

“As soon as it is dark,” replied Rex briefly. “Let’s go to the map-room and get the lie of the land. We’ve got to find a field somewhere within striking distance of that pin point.”

“I’ll go along to the sheds and see that the tanks are filled; I’ll join you in a minute,” said Tony as the car pulled up at the aerodrome.

They alighted, and Rex contemplated the aerodrome reflectively.

“Fairfax is either at that farmhouse or he is not,” he observed in a low voice, “but in any case it is from there that we shall have to start operations. We shan’t get far in these uniforms if there are people about—and I expect there will be. I think we had better wear those German Tommies’ uniforms we have in the cupboard. They’ll shoot us, anyway, if they catch us, so we are not taking any extra risk by wearing them; on the contrary, unless we meet one of the Varne crowd, which isn’t likely, it will be easier for us to get about. We’ll take some grub in our pockets in case we get hung up over there, and I might as well take some of that German money that was in Wistmann’s wallet. It might come in handy, you never know. Well, go and get the Bristol filled up and join me in the map-room, then we’ll try and get a bit of rest before we start.”

It was nearly dark when they took off and circled over the British lines, climbing for height; not until the altimeter touched sixteen thousand feet did Rex, still climbing, turn the nose of the machine towards the enemy sky. A few searchlights probed the air with their wavering beams, but at the height at which the Bristol was flying there was little to fear from them. For three-quarters of an hour they flew steadily on the course they had set; not a course which would take them immediately over their objective, but a route which took them to the right and brought them back behind it. This was a precaution upon which Rex had decided to allay suspicion in case they were heard.

When he was satisfied that his bearings were correct he cut off his engine and began a long glide towards the field he had selected for landing. It was far away from the lines and outside the area of normal operations, so he was not apprehensive that the field might be a pilot trap. The wheels touched the ground at last, and once again they sat listening for any sound which might indicate that their descent had been detected. A coppice at the far end of the field formed a ready-made hiding-place for the machine. They dragged the Bristol into it and discarded their heavy flying-kit, throwing it over the bottom plane ready for immediate use when they returned.

“This is the safest place we’ve landed in yet,” observed Rex. “As far as I could see from the map, there isn’t a building of any sort within half a mile. The farmhouse is up a road which turns off to the right about a mile and a half along the road over there on our right. There may be troops about, so we shall have to watch our steps.”

They made their way to the road and set off at a brisk pace in the direction of the farmhouse. The hedges began to thin out and the country became more open; presently they found themselves crossing an open heath with no cover within easy reach.

“I don’t think much of this,” muttered Rex, when they had travelled for some distance along the open road; “if anybody comes along they will certainly see us, not that it really matters, I suppose, now that we are so far away from Varne.”

He had hardly finished speaking when a motor-lorry rumbled into sight behind them, going in their direction. The sound of many voices singing was borne to their ears.

“Sounds like troops to me,” observed Rex, “and they seem to have had a merry evening. Keep straight on; they won’t pay any attention to us and it’s safer than dodging about looking as if we were trying to hide. It can be nothing unusual for troops to be walking about here and I should say they’ll pass us without a word.”

In this he was mistaken, however, for as the lorry drew level with them, they were greeted with a chorus of salutations.

“Come on,” shouted the driver, “get up behind—there’s plenty of room.”

“What made you start walking back?” cried a voice from within the lorry as Rex continued to trudge along without answering.

“You’ll get plenty of walking in the morning,” called another voice. “You come on in here or you’ll be late and I’ll get the blame for it.”

“That’s right, Corporal,” agreed yet another voice, “we shan’t get any more passes if fools start rolling up late.”

Realising that silence might lead to trouble Rex made the best of what he thought was an unfortunate affair, and with a quick nudge to Tony to follow him, sprang up in the back of the vehicle. He found himself with some eighteen or twenty German soldiers who were seated on wooden seats and on the floor. The driver slipped in the clutch and the lorry continued its bumpy way along the road.

The air was heavy with the smell of beer, sour bread and cheese, and Rex regretted more than ever that they had been obliged to join the party. He said nothing, but watched the country through which they were passing with interest, keeping a sharp lookout for the turning up which the farmhouse was situated. As they drew level with it the man on his left burst into a stream of lurid invective.

“Donner blitz! It’s my turn for extra guard to-night, curse it,” he ended sullenly.

“And mine,” said a voice opposite. “Don’t think you’re the only one.”

“I’m about sick of these guards,” went on the first grumbler. “I thought we came back here out of the lines for a rest, but it’s guards, guards, guards, morning, noon and night. Stable-guards, Headquarter-guards, gate-guards; I should have thought there were enough guards without starting another special guard, there’s no rest for anybody.”

“What is this special guard?” asked Rex casually.

“The new guard up at the farm. As if we hadn’t enough guards down at the camp, but they must needs start doing guards round people’s houses. What have they got to guard up there, anyway, I should like to know?”

“The Sergeant-Major says they’ve got a prisoner up there,” observed another, whom Rex noted wore the chevron of a Corporal. “I’m Corporal of the guard to-night, so stop grousing.”

“I’d swop my to-morrow’s rations for anybody to do my guard for me to-night,” said the first speaker, looking round hopefully, but the offer was received with a shout of laughter.

“Bah, you’re an optimist. I’d swop two days’ rations,” offered the second guard.

“You’re pretty generous, I must say,” sneered Rex, nudging Tony. “Who’s going to do a job like that for a chunk of rotten bread, I should like to know? Make it two pints of beer and two marks and I’m your man; I can’t sleep, any way, and I’d as soon stand up as lie down.”

“That’s a bet,” cried the other with alacrity.

“Here, hold hard,” exclaimed Rex, “you fix it with the Corporal first.”

“It’s all right with me, but where do I come in?” growled the N.C.O. “What do I get out of it?”

“Well, I’m not mean,” murmured Rex boastfully, “I’ll split the beer with you, Corporal, when we get to camp. Are you going to keep me company to-night, Koepler?” he added, turning to Tony.

“I’m not doing any guards for any two beers and two marks. Five marks is my price,” announced Tony loudly.

There was a titter of laughter followed by an argument which ended in Tony accepting four marks from the second guard, one mark to be handed over to the Corporal.

“Well, here we are, let’s go and get that beer,” said the N.C.O., “we’ve only got ten minutes before we fall in so we shall have to get a move on. Parade in marching order, rifles and bayonets, remember,” he added.

The lorry swung through the gates and past the Headquarter-guard of a camp which Rex saw at a glance was of considerable size.

“I don’t know what we’ve barged into,” he muttered to Tony as they alighted, “but I’ve taken the chance that this special guard is at the farmhouse we’re making for. If it is, it looks as if we’ve had a bit of luck.”

With the Corporal leading the way, and accompanied by the two men whose places they were taking, they made their way towards a big, well-lighted tent from which came sounds of revelry.

“Come across with those marks,” said Rex to his man, as they entered the canteen, and the soldier paid them over without a word. “Here! You’ll have to lend me your rifle and bayonet,” said Rex suddenly, “I’d forgotten that. I didn’t know I was to be on guard to-night, so I haven’t cleaned mine.”

“That’s all right,” answered the man at once; “I’ll fetch it in a minute. Fancy having one canteen for a place this size,” he went on, forcing his way through the crowd of soldiers towards the bar. “There’s ten regiments here already and I hear there’s more coming to-morrow.”

With some difficulty they managed to reach the trestle table at which drinks were being served and the Corporal’s eyes glistened when he saw the wad of notes in Rex’s hand, after Rex had insisted on paying for a second round of drinks.

“Gott in Himmel!” he gasped. “Where did you get that lot from?”

“My old man’s got more than he knows what to do with,” grinned Rex. “He’s made it out of the war and he keeps me well supplied.”

“Can you lend me twenty marks till payday, old chap?” said the Corporal quickly in a low voice.

“Of course I can, why didn’t you ask me before? I know a good sort when I see one—you can make it forty if you like. I say,” he dropped his voice to a whisper, “what about taking a bottle of cognac along to-night? It will be cold towards morning.”

“Good idea,” responded the Corporal, smacking him on the back. “I don’t mind doing a guard with a fellow like you. Keep it under your coat, though, and don’t let old Pulzer see it. He’s in charge of the guard to-night, and he’s an old devil.”

The cognac was quickly forthcoming. Rex pushed some notes into the Corporal’s hand and thrusting the bottle under his tunic, turned towards the door.

“Yes, it’s time we were getting our equipment on,” said the Corporal, glancing at his watch. “Parade outside the main gate, don’t forget—see you in a minute,” he added, hurrying off into the darkness.

Five minutes later Rex and Tony, complete in marching order with rifles and bayonets, made their way towards the gate where several similarly-dressed soldiers were standing about. The Corporal hurried up to them. “Here, you two,” he whispered, “don’t forget you’re taking Schmidt’s place,” he said, nodding to Rex, “and you’re Burnheim,” he told Tony. “When I call the roll, you answer for them. What about the booze? I’ll try and get you both posted to a quiet corner so that I can get a nip as I do the rounds.”

“Fall in, everybody!” snapped an Unter-Offizier, striding up. “Call the roll, Corporal!”

Rex and Tony took their places at the end of the line of troops. The Corporal produced a notebook from his pocket and called the roll by the aid of a flashlight. Altogether ten names were called and at the end the N.C.O. closed the book with a snap and turned to the Sergeant-Major with a brisk, “All present, sir,” and a moment later Rex and Tony were marching through the gates of the German rest-camp on the most audacious venture they had yet undertaken. Tramp, tramp, tramp, tramp, went the heavy boots on the road as they marched at attention towards the farm. A building loomed up in the darkness ahead. “Halt!” snapped the Unter-Offizier. “Left turn!” He strode off towards the door of the house.

“Is this the place, do you think?” whispered Tony.

“If it isn’t, we must be somewhere near it,” whispered Rex back. “As far as I can remember from the map this should be about the spot.”

The figure of the Unter-Offizier, accompanied by a cloaked officer, loomed up in the gloom.

“I want you to listen carefully to your orders,” said the officer, and as the sound of the voice fell on his ears Rex felt every muscle in his body go taut and the blood ebb from his face. He could sense that Tony was experiencing the same feeling and thanked Providence that there was no moon to expose their dumbfounded expressions. It was the voice of Major Trevor.

“You will take your stations where the Sergeant-Major posts you, and you will keep strict watch for anyone approaching. There is a prisoner housed in this building, and it is expected that an attempt will be made to rescue him. If anyone comes, the sentry will allow him, or them, to approach, and if necessary enter the house, but if they attempt to retreat it must be prevented at any cost. It is desired to catch the rescuers alive if possible, but if there is a possibility of their escape you will shoot. That is all. The Sergeant-Major will now post you.”

A few moments later Rex found himself standing in the shade of a yew-tree near the front of the house; Tony was stationed a few yards away on his right at the corner of an outbuilding. No one else was in sight and not a sound broke the eerie silence. Ten minutes passed slowly and then a sound of muffled voices came to Rex’s ears from a window near at hand, and through which streamed a pale shaft of yellow light. He took a pace or two nearer and after a quick glance around, risked a peep. He was back in his place in an instant, his heart beating wildly. Sitting by a smouldering log fire was Major Trevor and von Henkel, looking desperately ill and with his left arm in a sling. Rex edged a little nearer again and strained his ears to catch the words of their conversation.

Von Henkel was speaking, and appeared to be upbraiding Trevor for something. Rex caught a few odd words here and there. “. . . make another mistake . . . last chance . . . folly to risk keeping him here . . . get him out of the way. . . .”

Rex caught the name “Fairfax” and took a step nearer. “They’re not fools, those two,” he heard von Henkel say. “God knows what they might do, they have the luck of the very devil. I say it’s dangerous and unnecessary to keep Fairfax in this house; he ought to be behind bars at Lille, or else in the guard-room at the camp. I say send him down to the guard-room now and we can shift him to Lille in the morning.”

“Here, what are you up to there?” said a low voice near Rex’s elbow.

“Oh, I was wondering where you’d got to, Corporal,” answered Rex innocently. “Listen, they are talking of sending someone back to the guard-room”—he indicated the room behind him with a jab of his thumb—“and if we can click for the job it will be better than standing here risking the Sergeant-Major seeing us if we try to get a swig out of the bottle.”

“You get back to your place,” grumbled the Corporal. “If Pulzer comes round and finds you out of it, he’ll play hell.”

“Sorry,” said Rex apologetically, and stepped back into his place under the yew-tree just as the door opened and the Sergeant-Major appeared, calling loudly for the Corporal. The Corporal followed him back into the house.

He reappeared again almost immediately. “Schmidt, Burnheim!” he called sharply. “Fall in to escort prisoner,” he went on brusquely as the two sentries doubled forward. “We are going to escort a prisoner to the guard-room. Quick march—straight up the stairs, and jump to it—left—right—left—right—halt!”

The Sergeant-Major was standing outside a door on the first floor and he flung it open as they arrived. Inside the room, seated on the edge of a trestle bed, with his chin cupped in his hands, was Fairfax. He arose without a word and without so much as a glance at his escort took his place between them. “Forward march!” snapped the Corporal, and their heavy boots clattered down the staircase. The Corporal and Tony led the way and, as Rex brought up the rear, he noticed that the prisoner’s hands were tied behind him. Rex pulled his cap a little lower over his eyes as he saw Trevor waiting in the doorway below.

“You know your orders, sentries,” said the ex-Major as they passed him. “If the prisoner attempts to escape, you will shoot to kill.”

Rex breathed a sigh of relief as they passed into the darkness of the garden path and formed up abreast.

“You will soon have company, Fairfax,” called Trevor as they passed through the gate. “I expect your two young friends to arrive shortly; I’ll send them along to join you,” he sneered.

“Left—right—left—right,” snapped the Corporal as they marched down the silent roadway towards the camp.

“What about a drink, Corporal?” asked Rex when they were well outside earshot of the farm.

“All right, but we’d better not stop,” replied the Corporal. “Keep going and pass me the bottle.”

Rex groped in his pocket and produced the cognac. “Better let me have your rifle while you drink,” he suggested, and the N.C.O. passed over his weapon without a word. “Hold that a minute, will you, Koepler,” muttered Rex, passing the weapon on to Tony.

The Corporal raised the bottle to his lips. As he threw his head back to drink, Rex punched him with all his might in the pit of the stomach. He caught him by the throat as he fell. “And you hold that,” he added grimly. “Don’t run away, Fairfax,” he went on quickly as he saw the prisoner looking to right and left as if he intended to make a bolt for it. Rex heard a quick intake of breath and saw the prisoner lean forward in the darkness as if unable to believe his ears.

“Give me a hand, Tony,” grunted Rex as he knelt on the Corporal’s chest. “Give me the pull-through out of the butt-end of the rifle—that’s right.”

With the tough whipcord the new prisoner was swiftly bound hand and foot. A handkerchief was thrust into his mouth and kept in place by a rifle sling.

“Sorry, Corporal,” said Rex apologetically as the unfortunate German let out a muffled groan, “but I had to do it. You’ll get into trouble to-morrow, I’m afraid. Buy yourself something with this,” he added, thrusting a wad of notes into the other’s pocket. “I shall have to put you over the hedge, but I’ll drop a note to-morrow over this side of the lines in case you haven’t been found.” He picked up the cognac bottle and hurled it with all his might far into the field. “I’ve put that out of the way so that they can’t accuse you of drinking while on duty. That’s as much as I can do for you; you aren’t a bad sort.”

“Now,” he said, “have you cut Fairfax’s hands free, Tony? Good. Let’s get off, then; we’ll leave the talking until later.”

“My God, you’ve got some nerve, you two,” muttered Fairfax as they hurried across the heath in the direction of the Bristol. “Fancy marching me out right under Trevor’s nose; I’ve never seen anything quite like that.”

“How is it that Trevor is still alive?” asked Rex as they trotted along.

“Because he wasn’t killed,” grinned Fairfax. “When you saw him going down, the pilot did, as a matter of fact, sideslip right down into the ground, but Trevor was lucky enough to get away with it. He was rather badly burned down one side and has been swearing vengeance ever since. So has von Henkel. My bullet only went through his shoulder—missed his heart by about an inch, I heard him tell Trevor. I slipped up looking for that gun. Both Trevor and von Henkel had lost their jobs at Intelligence Headquarters, although they were, of course, at a field hospital for the time being. I was coming along a road the day after I had discovered the long-range gun, prepared to keep the appointment with my pilot, when I met them both face to face. I was disguised, of course, but it did not deceive them. I thought it was all up and no mistake.”

“Keep quiet now,” broke in Rex, “the Bristol is in the corner over there under the trees. I don’t think it will have been found. You’ll have to squeeze in the back seat with Fraser. It will be a heavy load, but I have a long run to take off in. Here she is, all clear. Swing the prop., Tony.”

They took their places as the engine started. Rex swung round into the slight breeze, raced across the turf and then zoomed into the starry sky. At two thousand feet he levelled out and turned his nose towards home and safety.

*      *      *      *      *

“The General is mighty pleased with you two lads, I can tell you,” said Fairfax the following morning when they met to talk over their adventure. “He was shaken when I told him how you had kept out of that trap and how you had pulled me out of it. He was still more pleased when I gave him the position of the German gun.”

“But he knew that already,” said Rex quickly.

“Knew it! Don’t be silly. You don’t suppose the position marked on that dud message was correct, do you? What happened was this. They sent that pigeon home, which, by the way, was one of mine, with the idea of getting you out there. They knew that there was a good chance of somebody being sent to fetch me and they hoped it would be you. Giving the position of the gun incorrectly has cost our people probably a quarter of a million pounds, shelling and bombing an empty wood. You see, if Trevor and von Henkel could have hauled all three of us before the authorities it would have been a feather in their caps and might have got them once more in favour with the Higher Command.”

“I should like to see his face when he discovers how we walked out with you,” laughed Rex. “Well, that makes us quits, anyway.”

“Well, I must be getting along,” said Fairfax. “Thanks very much for getting me out of a tight corner.”

“Bosh,” grinned Rex, “people in our profession don’t look for thanks. It will probably be your turn next time!”

TRANSCRIBER NOTES

Misspelled words and printer errors have been corrected. Where multiple spellings occur, majority use has been employed.

Punctuation has been maintained except where obvious printer errors occur.

Some illustrations were moved to facilitate page layout.

[The end of The Spy Flyers by Capt. W. E. (William Earl) Johns]