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Title: Biggles Hits The Trail

Date of first publication: 1941

Author: Capt. W. E. (William Earl) Johns (1893-1968)

Date first posted: Dec. 3, 2020

Date last updated: Dec. 20, 2020

Faded Page eBook #20201206

This eBook was produced by: Al Haines, Cindy Beyer & the online Distributed Proofreaders Canada team at https://www.pgdpcanada.net

CAPTAIN W. E. JOHNS

Biggles

Hits The Trail

OTHER BOOKS BY CAPTAIN W. E. JOHNS
 
BIGGLES FLIES NORTH
BIGGLES FLIES SOUTH
NO REST FOR BIGGLES

Biggles Hits the Trail was first published in the U.K. in 1941 by Oxford University Press. This edition was first published in 1962, and was reprinted in 1969, by May Fair Books Ltd, 14 St. James’s Place, London, S.W.1, and was printed in Great Britain by Love & Malcomson Ltd, Brighton Road, Redhill, Surrey, England.

Major James Bigglesworth, better known to his friends as Biggles, pushed his coffee cup aside, rapped on the table sharply with the handle of a spoon, rose to his feet, and looked from one to the other of his two guests with an expression of quiet amusement.

‘What are you going to do?’ inquired Algy Lacey, his comrade of many adventures, who sat on his left.

‘I’m going to make a speech,’ replied Biggles seriously. ‘I’ve never made one before, and I don’t expect I shall ever make another, but I think an occasion like this demands one. It is the first time——’

‘Absolutely, old lad,’ declared Algy, ‘but don’t be too long about it because I want to switch on the wireless. Menovitch is playing the Grieg Concerto at nine o’clock, and I want to hear it.’

Biggles frowned. ‘Whose dinner-party is this, anyway; whose room is it, and who’s making the speech, me or you?’ he inquired, coldly.

‘Ha! Did you hear that, Ginger?’ interrupted Algy, glancing across the table at a sandy-haired, freckle-faced youth. ‘He called us gentlemen——’

‘Will you shut up?’ snapped Biggles. ‘You never could behave like a gentleman, even in Mess. I only called you one as a matter of form; there’s no other way to start a speech.’

Algy looked pained. ‘Did you hear that, Ginger?’ he complained. ‘He’s casting nasturtiums——’

‘Gentlemen,’ resumed Biggles, with a withering glance at Algy, ‘I feel I should fail in my duty if I allowed this auspicious occasion to pass without a few words on the reason for this festive gathering tonight. As you are aware, we sent our guest of honour—who, as we are all friends, I will call by his apt if undignified pseudonym, Ginger—to Brooklands Aerodrome for a course of instruction in the art of flying, and its allied subject, ground engineering. Last week he was tested for his Pilot’s ‘A’ Licence, and yesterday notification of its award was made by the Royal Aero Club.’

‘All right, once was enough; no one asked you to sing a song, did they?’ frowned Biggles. ‘But to continue,’ he went on, taking a letter from his pocket. ‘I have here a letter from Pim Carthorne—I mean Captain Carthorne—his instructor, and in it he speaks highly of the progress made by his pupil. I do not propose to read it, because, while praise is good when taken in small doses, too much is apt to cause a swollen head. Let it suffice that Pim—Captain Carthorne—has been good enough to say that his pupil on this occasion shows more than usual ability in the handling of an aircraft, and should turn out to be a first-class pilot. Further, perhaps on account of his zeal, his knowledge of care and maintenance and aero engines is equal to that of many qualified ground engineers. He concludes, however, by deploring his promiscuous employment of American slang, which he claims is likely to affect adversely any self-respecting British aeroplane.’

Biggles folded the note and put it in his pocket. ‘Before I offer you my heartiest congratulations, Ginger,’ he went on earnestly, turning his keen eyes on the blushing youngster who sat on his right, ‘I am going to give you a word or two of advice—from an old-timer to a beginner, so to speak. It is this. Do not set too great a store on such knowledge as you have acquired, which after all, at present, is very little. You can fly, and have flown, an aeroplane, which means that you are master of a machine. But never, never let your confidence outrun your discretion, for if you do you will be lucky if you live long enough to regret it. Never forget the fact that you are only allowed to visit the world above your earth-tied fellows on sufferance. By your art—call it a trick if you like—you have learned to overcome a great natural force—gravity; and you cannot flout Nature with impunity. Treat Nature with respect and she will tolerate you, even encourage you; but treat her with contempt, and your days are numbered. You know a little now, and when you have six thousand hours logged, as I have, you will know more; but that isn’t everything, and you will still be only a puny mortal at the best. Never forget that.

‘And finally, bear in mind that you owe something to those pioneers who made this great thing possible. Honour the traditions of courage, modesty, and faithfulness in little things that they have set down as a guide for you to follow, and you will always be welcome at any place where airmen meet, for they will know you for what you are, even though they do not speak of it. Fail in those qualities, and you will be less than a pariah slinking around the tarmac for such crumbs of good-fellowship as he can find. And now I am going to ask Algy to stand up and join me in drinking the health of the fledgling who we both hope will be a credit to his machine, to us, and aviation as a whole, in the old R.F.C. toast. Soft landings!’

Biggles sat down and reached for a cigarette. ‘All right, Algy, you can turn the wireless on now,’ he said. ‘We’ll call on Ginger to reply to the toast presently.’

Algy glanced at the clock and hurried to the instrument. ‘It’s a bit late, I’m afraid,’ he said quickly, as he switched on and waited for the valves to warm up.

A voice, faint at first, but rapidly increasing in volume was speaking . . . ‘few minutes late. Now before we begin here is an S.O.S.’

‘Oh, confound these S.O.S.s,’ grumbled Algy. ‘I’ve never heard of any one answering. . . .’ The words died away on his lips as the voice of the announcer continued.

‘Will Major James Bigglesworth—B-I-double G-L-E-S-W-O-R-T-H, Major James Bigglesworth, last heard of at Brooklands Aerodrome, go at once to Brendenhall Manor, Buckinghamshire, where his uncle, Professor Richard Bigglesworth, is dangerously ill.’

‘I am requested to add,’ continued the voice, ‘that if Major Bigglesworth receives this message, and goes to Brendenhall, he is advised to exercise the same caution as on the occasion of his last visit—whatever that may mean. . . . And now we are going over to the Albert Hall for——’

Click! Algy snapped back the switch, and as the voice ended abruptly, swung round on his heel to face his partner. ‘Well,’ he said crisply, ‘what do you make of that?’

Biggles shook his head; a worried frown creased his forehead. ‘Dickpa’s ill, obviously, but there’s more to it than that. I don’t like the sound of that last sentence, and that’s a fact. What was it? “Exercise the same caution as on the occasion of his last visit.” That’s a fair warning, Algy. You remember our last visit—eh?’

‘I can’t stop to tell you about it now,’ said Biggles shortly. ‘Dickpa—he’s my uncle—I’ve always called him Dickpa since I was a kid—was having a desperate time with a gang of American desperadoes on account of a secret he held. That message means that he’s in trouble; it can’t mean anything else.’

‘But how did he get word to the B.B.C., if he’s ill? Who told the B.B.C. about it?’

‘I don’t know, but I’ll soon find out.’ Biggles crossed swiftly to the telephone, ran through the pages of the directory until he found the number, and then dialled it. ‘Hello! Hello! Is that the B.B.C.? This is Major Bigglesworth speaking. I’ve just received your S.O.S. Can you oblige me by telling me how you received that information? . . . Thank you.’ He glanced at Algy. They’re putting me through to another department,’ he explained. ‘Yes—Major Bigglesworth speaking,’ he went on quickly, turning again to the instrument. ‘Yes . . . sorry to trouble you, but it may be very serious . . . what’s that? . . . Where? . . . Brendenhall Station. . . . I see. . . . Thanks very much. . . . Thank you. . . . Goodbye.’ He replaced the receiver and turned to the others who were watching him expectantly. ‘The message was sent in by Lord Maltenham,’ he said, curtly.

‘I have no idea. Not the remotest. It doesn’t really matter, though. What does matter is that he has left a note for us with the station-master at Brendenhall Station; we are to call for it and read it before going on to the house.’

‘But how the dickens did he know that you would ring up the B.B.C.?’ inquired Algy.

‘He didn’t know it, but I expect he hoped I would. After all, it was a pretty obvious thing to do. The B.B.C. say that they were asked not to broadcast the message about the note at the station, but if I rang up they were to tell me. This fellow Maltenham’s no fool apparently. It sounds to me as if there’s some dirty work going on. Come on; let’s be getting along.’

‘Of course; where else? Sorry we can’t finish the party. Ginger, but this is urgent. We’ll finish it another day. You haven’t met Dickpa, of course. He’s a grand chap—explorer. You may remember my telling you about our treasure hunt in the Matto Grosso, in South America. Well, he’s the chap we took—here, where are you off to?’

‘To get my hat and coat,’ replied Ginger, instantly. His face was flushed with excitement and his eyes sparkled. ‘I’m coming with you, aren’t I?’ he asked anxiously.

Biggles hesitated. ‘Yes, I suppose you can come,’ he muttered slowly. ‘Be careful what you’re up to, though; I’ve got a feeling there’s trouble ahead.’

‘That’s what I thought, otherwise I shouldn’t be so anxious to come,’ returned Ginger, coolly.

‘I thought that was what you were thinking,’ declared Biggles. ‘All right. What’s the time? Nine-thirty. My car’s in the garage round the corner. It’s a straight run down to Brendenhall, and provided it keeps fine we should do it in an hour. Just a minute.’ He crossed to the desk, took out a service Webley revolver, loaded it from a packet of cartridges that lay beside it, and dropped it into his pocket. ‘It’s always as well to be on the safe side,’ he observed, carelessly. ‘Come on, then; let’s get away.’

Exactly fifty-five minutes later Biggles’s Bentley pulled up with a groaning of brakes outside the small country station of Brendenhall. Two oil lamps cast a dim, yellow radiance on the platform, and a single lighted window revealed the booking-office.

‘Well, here we are,’ he observed, as he opened the door and stepped out. ‘You might as well come in with me and we’ll see what Maltenham has to say in his note.’ He led the way to the booking-office pigeon-hole. ‘I’m Major Bigglesworth,’ he told the clerk behind the grille. ‘You have a message for me, I believe?’

‘Here you are,’ replied the man immediately. ‘A gentleman left it about an hour and a half ago; he said you might be calling, but he couldn’t stop.’ He passed over the envelope.

‘Thanks.’ Biggles tore it open impatiently as he walked quickly to one of the outside lamps. ‘I’ll read it aloud,’ he said. ‘Dear Bigglesworth, Get up to the Hall as quickly as you can, but watch your step; there are some funny people about in the park. If you are driving, go slow and keep your eyes open. If you see a blue light, go for dear life. Your uncle has been hurt, so I must get back to him. He’s alone, and I’m afraid. I’ll tell you the rest when I see you. For God’s sake be careful. Yours, Maltenham.’

‘Not so good, eh?’ murmured Algy softly. ‘I suppose there isn’t any chance of this lad Maltenham being off his rocker?’

‘That letter sounds sane enough to me,’ replied Biggles grimly, ‘but it’s thundering mysterious,’ he added. ‘I wonder what this blue light is that he talks about—but there, it’s no use guessing. Let’s go. Algy, you take my gun; if any skunk takes a crack at us let him have it, but shoot low. We don’t want any inquests if we can possibly prevent it. Ginger, you keep your eyes skinned, but keep your head down if there’s any trouble.’

‘A couple o’ miles or so. The last mile is up a private drive,’ answered Biggles, as the car shot forward into the night. He ran on his side-lights only until he reached the drive, but as he turned slowly into the narrow entrance he flicked on the powerful headlights. They blazed like twin searchlights through a long avenue of horse-chestnuts, backed by heavy pinewoods, but there was not a sign of life as far as they could see, although a bend in the road a quarter of a mile ahead hid the house from view.

‘No, but I expected to. I’ve never turned into this drive before at night without seeing one or two rabbits scuttle across it. There’s somebody about, I fancy.’ Biggles slowed down to a steady twenty miles an hour, but as nothing occurred his apprehension wore off and he increased the speed to thirty-five. He reached the corner, and with the old Elizabethan house now in view, he was about to put his foot down on the accelerator when a yell of warning broke from Ginger’s lips.

‘Look out—the tree!’ he shouted, and with his hands over his face, flung himself on the floor of the car.

Biggles saw it at the same moment. A great elm that flanked the drive fifty yards ahead was moving; with a slowness that was awful in its deliberation, it was falling straight across the road. There was no time to think, and he acted instinctively with the same speed that had more than once saved his life in the air. His heel crushed down the foot-brake while he grabbed the hand-brake and flung his weight on it. Instantly all four wheels locked. Fortunately the road was dry, but even so the heavy car skidded wildly as the wheels bit into the yielding gravel with a grinding scream that was lost in the mighty roar of sound as the huge tree struck the ground.

From first to last the whole thing was a matter of perhaps three seconds. It was touch and go. Carried on by its own volition, the big car swung sickeningly, and it was only due to the fact that the left side wheels went off the road and sank into the turf, dragging the car round to the left, that the party escaped annihilation. As it was, there was a splintering crash as a branch struck the bonnet and sheered through the windscreen in a cloud of flying splinters. The lights went out. Then all was silent.

Biggles was on the ground first, crouching forward, eyes probing the darkness ahead, behind, and aside. ‘Give me that gun, Algy—quick,’ he snapped. ‘Either of you hurt?’

Silence, a brooding uncanny silence, fell, and Biggles slowly straightened his back. ‘Could it have been a fluke—an accident?’ he muttered.

There was no need to point. From a spot some little distance ahead a cold blue radiance appeared. There was no central point to the light, which appeared to have no beginning and no end; rather was it like a beam of phosphorescent mist creeping slowly through the night air in their direction. For a moment or two they watched it, fascinated by the phenomenon, and then Biggles sprang back in alarm. ‘It’s blue,’ he gasped. ‘It’s the blue light. Run for it—this way,’ He dashed off into the trees with the others at his heels.

At the first sound of their footsteps the light had increased in intensity and probed feelingly towards them. Biggles stopped suddenly and swung round with an angry snarl. ‘I’m not going to bolt from a confounded light,’ he grated, and jerking up the revolver, sent three shots crashing in quick succession in the direction of the beam. As the third spurt of flame leapt from the muzzle the light jerked suddenly and came to rest on his upraised arm, which remained motionless, picked out in lines of blue fire.

The others heard him catch his breath spasmodically, saw his fingers jerk open convulsively and the revolver fall to the ground. Then he sprang back and dashed past them. ‘Run,’ he cried in a curious high-pitched voice. ‘Run for your lives, and don’t stop.’

Side by side, stumbling and tripping over unseen obstacles, striking their faces on low-hanging branches, they tore through the wood. ‘This way—bear round to the right—let’s try and make the house,’ panted Biggles, as they raced on.

For what must have been half a mile they ran as they had never run before, and then, after a glance behind, they began to slow down.

‘Don’t talk—keep going,’ snapped Biggles, and it struck Algy that he had never seen him so shaken. ‘This way,’ he went on. ‘I used to birds-nest in this park when I was a kid, so I know every inch of it. There should be a footpath about here—yes, here it is. Good! This will take us up by the back of the gardener’s cottage to the house. I think we’ve given them—or it—the slip, but keep your eyes open.’

‘I can’t help that. I wouldn’t go back to that place for fifty cars—not now, anyway. Quietly now; if these blue-light merchants have decided that we’ve got away they might make straight for the house to prevent us from getting in; they must know that’s where we were bound for.’

‘I’m hoping Malty—this Lord chap—will be there to open the door for us. Here we are; quietly does it.’ Biggles stopped and peered ahead intently, listening, with every nerve taut.

Immediately in front of them, at a distance of thirty or forty yards, loomed the black mass of the old house. Not a light showed anywhere. The track they were on diverged a few paces ahead, one path turning to the left through a thicket of sombre, evergreen shrubs, and the other joining the weed-covered main drive where it swung round in a wide circle before the front door.

‘Let’s get a move on,’ muttered Algy irritably. ‘I’m getting the willies standing here. This is the sort of place where anything might happen—anything.’

‘You’ve sure said a mouthful,’ agreed Ginger. ‘Come on Biggles, let’s go.’

‘Right,’ snapped Biggles. ‘Run for it.’ Suiting the action to the word, he broke cover, and with the others close behind, sprinted for the front door. Reaching it, he twisted the old wrought-iron handle and put his shoulder against the massive oak portal, but it did not budge an inch. Casting all attempts at secrecy to the winds, he beat upon the panels with his fists. ‘Maltenham! Maltenham!’ he yelled. ‘It’s me—Bigglesworth. Open the door.’

There was no reply. Silence, utter and complete, hung over the place like a pall, and he felt a thrill of apprehension run through him. Frantically he kicked the lower panel with the toe of his boot. ‘Maltenham—Dickpa, open the door!’ he shouted again.

The ringing echo of his voice floated back eerily from the woods, but there was still no sound from the house. He moistened his lips and turned to the others. ‘I don’t like this,’ he muttered, turning again to peer into the gloom to left and right. ‘Either they’re not here or else——’ He did not finish the sentence.

‘Well, let’s break in, for heaven’s sake,’ exclaimed Algy. ‘Either my nerves are not what they used to be, or else there’s a blight on the place; I feel that if a mouse squeaked I should scream.’

‘For goodness’ sake, pull yourself together,’ Biggles told him angrily. ‘It’s no use trying these lower windows: they’re barred, as you know. We’d better try that side pantry window—the one—My heavens, what’s that!’

Shrill and clear through the still night air from somewhere in the wooded heart of the park came the long-drawn scream of a man in mortal fear. It rose to a high, palpitating falsetto and then ended abruptly.

It was so horrible that for a moment the three airmen remained rooted to the ground; Ginger was unashamedly clutching Algy’s arm, while Biggles, his face deathly pale in the wan star-light, peered into the darkness in the direction of the sound. For an instant or two he hesitated, and then threw up his hands in a helpless gesture. ‘Sounds like murder being done,’ he muttered harshly, ‘but we can’t do anything in the dark, and unarmed. Pray heaven it isn’t Dickpa. Come on, let’s get inside. Keep close.’ He led the way round to the side of the house and halted under a small square window. ‘I’d better go in because I know the way,’ he went on. ‘When I’m inside you slip round to the front door and I’ll let you in. Give me a leg up, Algy.’

He took out a box of matches, held them between his teeth, seized the window-sill in his hands and vaulted up. There was a tinkle of falling glass as he shoved his elbow through the pane. The window swung open and his lithe body disappeared through the small aperture. For a moment his face showed dully white in the black opening. ‘O.K.,’ he breathed. ‘Get round to the front door.’

He struck a match and hurried down the corridor that gave access to the breakfast room, from which a door opened directly into the huge hall. On his way he picked up a heavy silver statuette from a small table, and holding it by the head, swung it as a weapon; but he reached the front door without incident and threw back the chains and bolts.

Algy and Ginger literally leapt inside. ‘Get a light on the scene, for the love of Mike,’ implored Algy.

Biggles crossed swiftly to a large oil lamp that stood on the centre table, lighted it, and looked around swiftly. ‘My gosh! there’s been trouble here all right. Look at all this,’ he said. ‘The place looks like an arsenal.’

Right across the table lay an enormous double-barrelled elephant gun. Beside it was a hammerless twelve-bore, a .410 collector’s gun, and a small rifle. Leaning against the window that overlooked the drive was an Express rifle. Several broken boxes of cartridges were scattered about. A number of spears and cutlasses that normally decorated the walls had been taken down and were standing or lying in handy positions.

Biggles picked up the elephant gun and snapped open the breach. ‘Loaded,’ he said laconically, as he closed it again and replaced it on the table. ‘Where’s Dickpa? That’s the first and most important matter to attend to. Lock that door, Algy, and we’ll go upstairs; I know where his room—hark!’ The last word was a high note of warning. He snatched up the elephant gun and made a dash for the door. ‘Sounds like somebody coming,’ he added tersely.

Footsteps were coming down the drive; they were those of a man running in stark terror, and if confirmation of this were needed, the loud gasping sobs for breath of the runner supplied it.

‘You stand by to guard the door,’ yelled Biggles, and dashed into the open in the direction of the approaching footsteps. Dimly through the gloom he could just make out the dark form of a man who swayed from side to side as he raced towards the house. Behind him, silent, yet dreadful in its ghostly deliberation, danced a stream of blue mist. Biggles brought the gun to his shoulder. ‘Halt! who goes there?’ he roared.

The runner threw up his hands. ‘Shoot! Shoot!’ he screamed. ‘I’m——’ He stumbled and pitched face downwards on the gravelled drive.

Biggles’s lips parted in a mirthless smile as his fingers tightened over the triggers. He did not take aim for the simple reason that there was no mark to aim at except the uncertain light. Two long streaks of orange flame leapt from the twin barrels as the gun thundered out its heavy charges in a quick left and right. The blue light disappeared instantly. Bang! Bang! Algy’s twelve-bore blazed into the darkness, the spraying shot rattling on the bushes like hail. Crack! A flash came from the doorway, and a bullet ricocheted up from the road with a shrill whe-e-e.

‘Careful with that rifle, Ginger,’ shouted Biggles. ‘Come on, Algy—take his feet.’ He bent over the fallen man and seized him by the collar. Half dragging and half carrying, they managed to get the prostrate form into the hall, where they dropped him on to the hearthrug.

‘Shut that door, Ginger, bolt it and re-load the guns,’ ordered Biggles. ‘Algy, pass me that decanter off the sideboard. I believe this is Maltenham, and he looks in a bad way.’

Algy dashed to the sideboard and returned to where Biggles was removing the unconscious man’s collar. ‘That’s the idea,’ muttered Biggles, as they managed to get some of the liquid through his lips. ‘Not too much—we don’t want to drown him. Hello, what now?’ They both sprang to their feet as a new sound reached them. Standing at the foot of the stairs, hanging on to the banister, was a white-robed figure that held an automatic unsteadily in its right hand.

‘Dickpa!’ Biggles’s joyful shout eased the tension. ‘Be careful with the gun—it’s me, Biggles,’ he added quickly.

‘Thank God you’ve come,’ whispered the Professor fervently. ‘Great heavens! what’s happened? Don’t tell me they’ve got poor Maltenham!’

‘I don’t think so. It’s only shock and exhaustion I fancy. They were after him, but we managed to get him inside just in time. But what’s the matter; you look ill?’

‘I am. I shouldn’t have got up really, but I heard the noise. How did you get in? I must have been in a dead sleep; neither Maltenham nor I have slept for days.’

‘Well, you get back to bed,’ Biggles told him. ‘We’ll bring Maltenham round, and then perhaps you’ll tell us the meaning of this unpleasant state of affairs.’ Biggles turned to Algy. ‘See Dickpa up to his room,’ he ordered. ‘And you, Ginger, watch the drive through that window and let me know if you see anything unusual.’

Half an hour later the Professor, propped up in bed, told his story while Biggles, from a box-seat in the window, kept a watchful eye on the front door. Algy and Ginger sat on guard by the other window, while Lord Maltenham, little the worse for his adventure, reclined in an armchair near the bed. He was a delicate-looking young man of not more than twenty-one or twenty-two years of age, with a high, intellectual forehead and rather sad, dreamy eyes. A long upper lip betrayed the thinker, rather than the man of action, and Biggles was wondering how his uncle had become associated with him when the Professor began to speak.

‘I suppose you must be wondering what is going on here,’ he observed. ‘And why I—or perhaps it would be more accurate to say we—should have to resort to the desperate expedient of sending for you by the radio.’

‘Yes, naturally I have wondered,’ replied Biggles readily. ‘I expected to find you desperately ill, but as far as one may judge, there doesn’t seem to be very much the matter with you, if I may say so.’

‘True. To be quite frank, there is little wrong with me at the moment except weakness, and nerve trouble brought on by the experiences I am about to relate. I am afraid Maltenham exaggerated my illness to the B.B.C. officials, but we wanted you here, and we didn’t know your address so there was nothing else for it. In any case, it is as well for you to know about the strange things that have happened, because if anything tragic occurred—well, neither Maltenham nor I is unknown to the world, and questions might be asked.’

‘Oh, quite—quite. I merely remarked—But let me tell the story, then you’ll understand what we are up against. Speaking from memory, it must be nearly two years since we last saw each other. You were anxious to go off on a flying trip, while I was equally anxious to pursue my studies in other directions, or, to be more precise, in the Far East, a locality that has always interested me intensely.

‘Well, I had booked my passage and made all the necessary arrangements when, two days before I was due to sail, I had a visitor. It was the son of my old friend, the Earl of Maltenham, and he was in great trouble.’ Dickpa threw a glance in the direction of the subject of his conversation. ‘May I tell them?’ he asked.

‘Good,’ continued the Professor. ‘As I was saying, Roger—that’s Maltenham’s Christian name, by the way—came to see me. At that time he was a medical student. His father had recently died, leaving him a large sum of money, but that could not help him. To be quite frank, he had, like many medical men before him, discovered the deplorable properties of certain drugs to which he had access, and from casual curiosity he had rapidly acquired a taste which he was well aware would ultimately destroy him. Realizing his danger, he asked me to save him by taking him with me, where he knew he would be beyond the reach of temptation. In short, he suggested abandoning his medical career, which was not of real importance, and coming with me to China. Naturally, I agreed, and we went.

‘Six months later we were far in the heart of Western China, on the borders of Tibet. Few people realize the size of Tibet. To tell you it covers a million square miles would mean little, because the brain fails to grasp what that really means. You are airmen, so let me explain in your own way. The country is as long as from London to Constantinople, and as wide as from London to Gibraltar. Which means that you could get most of Europe into it quite comfortably. An area of roughly a quarter of that vast expanse of land is uninhabited—or is supposed to be. Europeans have barely touched upon the fringe of it, possibly because there is not a railway within four hundred miles of its frontiers, which in turn is no doubt due to the fact that it lies at an altitude of between thirteen thousand and sixteen thousand feet above sea-level. So much for Tibet. I merely mention this in order that you may better understand what is to follow.

‘Now while we were on the western frontier of China, which is also the eastern frontier of Tibet, we heard a curious native rumour of a mountain, known as the Mountain of Light, which according to report held some strange properties. For example, people who dwelt near it never suffered from any form of illness, and lived to a great age. At first we discountenanced these tales, but as they persisted, and no matter where we went the natives always pointed in the same direction, we were forced to conclude that there must be some foundation of truth in them. Having decided that, it will not surprise you to learn that we attempted to verify the story by personal experience. And that was the beginning of our troubles, for of all the unusual circumstances that thereafter attended us, one fact alone was clear, and that was that the mountain was guarded by powers against which we could do nothing.

‘It would take me too long to tell you now of all the dangers that beset us. But they were real, very real, and ultimately we fled, thinking that with our departure our perils would cease; but in that we were mistaken, sadly mistaken, as we were soon to learn. The fact that we were willing to depart evidently did not satisfy those who, for want of a better name, we will call the guardians of the mountain. No! The fact that we knew of the existence of the mountain was sufficient to jeopardize our lives, and I am convinced that we only escaped death by a merciful Providence, in the shape of a snowstorm which caused us to lose our way, and instead of trekking to China as we intended, we finally forced our way over the Himalayan passes and then through the jungle to India, or rather, Burma. Our presence in India was noted in the newspapers, and forthwith the persecution started afresh. Again, I cannot tell you of the many narrow escapes we had. On one occasion we were the innocent cause of two planters losing their lives. The rest-house was full, so we gave our rooms up to them because they were both very tired. In the morning they were both dead—without a mark on their bodies. The murders were a mystery to every one except us, for we knew that the fate that had overtaken them should have been ours.

‘And now I come to the most alarming incident of all, and one that may open your eyes to the mysterious forces that surrounded us, and still do surround us, if it comes to that. We were followed right across India, but when we finally sailed from Bombay on the Calamore Castle we thought, naturally, that our troubles were at an end. Again we were mistaken. Now I want you to listen to me very carefully, but kindly reserve your remarks until I have finished.

‘The first night out from Bombay, Roger and I were lying in our stateroom, trying to go to sleep. We had booked rather late, so we could only get a double-berthed cabin; not that it mattered. In fact, as it turned out it may have been a good thing. Roger was already half asleep and I was just dozing off when I saw the lid of my cabin trunk slowly opening. I may mention that it was still quite light in the cabin, because I am not a good sailor and I had deliberately left one light burning in case I had to get up. Now I am not nervous, and for some seconds I watched the trunk with a sort of detached curiosity, thinking perhaps it was a trick of the eyes, or an illusion caused by the movement of the boat. But when I saw that the lid was quite definitely opening I knew without doubt or question that somebody was inside it. Cabin trunks do not open themselves—at least, not those we are accustomed to in England.

‘As soon as I realized this I reached for the small automatic I had bought in India, which was in my jacket pocket, and then jabbed Roger in the back to wake him up. This movement was evidently seen by the fellow in the trunk, for the lid closed again quickly with a very definite click. I heard it, mark you, as well as saw it. I leapt out of bed with a shout and sprang on the lid of the box to keep it shut while Roger came to my assistance. Now it looked as if we were in for a fine old row, so to be on the safe side I told Roger to ring the bell while I remained on the box. A steward answered the summons, but I told him that as we had a potential murderer in the room he had better fetch an officer. He did. Still sitting on the box, I explained to both of them what had happened, and asked the officer to take the man in charge.

‘With that I got off the trunk and the officer invited the occupant to come out in no uncertain terms. There was no response, so he opened the lid and looked inside.’ Dickpa coughed and looked at his nephew apologetically. ‘Biggles,’ he said evenly, ‘believe me or believe me not when I tell you that the trunk was empty. By empty I mean that there was not a man in it. There were two other objects: a nasty-looking dagger and a small bottle made of very curious glass.’

‘I was prepared for you to say that,’ observed Dickpa. ‘No, I did not have a nightmare. I——’

‘But wait a minute,’ interrupted Biggles, ‘I don’t get the hang of this. You say the box was empty. Well, that’s that: why make a fuss about it?’

Biggles shook his head. ‘I give it up,’ he confessed; ‘I’m no good at conundrums. Either there was some one in the box, or there wasn’t. You say there was no one in it. If that was so——’

‘Just a minute, let me finish,’ broke in Dickpa. ‘Naturally, I was flabbergasted, and felt a bit of a fool, particularly as the officer looked at me in a condescending way that said as clearly as words that he suspected I had been drinking. Then I happened to examine the cabin trunk and found that it was not my trunk at all. Mine had been pushed under the bunk, while Roger’s, which is one of the wardrobe sort, was standing on end against the wall with the door open. Neither of us had ever seen the third trunk before. Briefly, I told the officer that I would not be responsible for it, and moreover I would not have it in my room in any circumstances whatever. I helped him to rope the thing up, and then he took it away, both he and the steward grumbling at the weight of it.

‘We heard no more about it, and had pretty well forgotten about the whole affair by the time we reached England; but as we were about to leave the boat at Southampton we were sent for by the captain. I must tell you, however, that as the Calamore Castle steamed into Southampton Water she ran into a dense fog and collided with a Norwegian tramp that was going out. The Calamore Castle was damaged below the waterline, and was leaking badly, but not dangerously, when she docked. You may have read about it in the papers. The water got into the hold, so the luggage was pulled out and put on deck, where it was examined by the Customs people before being released. When they came to the trunk that had been in my room no one claimed it, so they cut the cords and opened it.’ Dickpa paused to let the words sink in.

‘Go on,’ said Biggles impatiently. ‘What did they find in it? A cage of white mice?’

‘Of course. The trunk had been submerged and the fellow had evidently been drowned.’

‘But you can’t have it both ways,’ declared Biggles. ‘Either the box was empty or it had a man in it. It couldn’t be empty and have a coolie in it at the same time. What are you trying to tell me?’

‘And then roped it up on the outside with my special knots? No, that won’t do.’

‘Are you asking me to believe that the trunk was corded up exactly as it had been when you last saw it?’

‘My knots had not been undone, I’ll swear to that. The ropes were the first thing I looked at.’

Biggles frowned. ‘Have you had a touch of fever lately, Dickpa?’ he inquired.

The Professor smiled. ‘I’ll forgive you for a natural, if rather pointed, remark,’ he said. ‘No, I haven’t had a touch of fever for some time.’

‘Then the fellow must have crawled through the keyhole,’ declared Biggles emphatically. ‘There was no other way in.’

‘You wouldn’t have thought so if you had seen him,’ returned Dickpa. ‘He was a hulking great brute. But let me go on; we won’t discuss possible solutions until you’ve heard the whole story.’

‘My goodness! You’re not going to tell me that you’ve any more stories like the last one, I hope.’

‘The next one is worse, if anything. At any rate, it’s just as inexplicable.’

‘Then for goodness’ sake fire away and let’s get it over,’ invited Biggles. ‘Nothing less than chloroform will make me sleep tonight, if you go on like this.’

‘I will pass on then to the time we reached home,’ continued Dickpa. ‘For some days nothing happened. Roger and I were kept busy looking after ourselves, keeping the place ship-shape and going over maps, with a view——’

‘To be quite truthful, it is. There seemed to be no point in it. But don’t interrupt; let me get on with the story. The day before yesterday I was sitting here by the open window writing up my field notes. Roger had gone for a stroll, taking the forty-four rifle with him in order to try to get something for the pot. I suppose I must have dozed, but suddenly I was alert, conscious of danger; that’s the only way I can explain it. I could have sworn some one was in the room, but I could see nobody, so I sat down again, blaming myself for letting my nerves get into such a state. Then I saw something. It appeared to be a sort of blue light, a ray that began at an indefinable point near the door and shone across the room in my direction. At the same time I became aware of an unpleasant numbing sensation, and the room began to grow dark.

‘I fancy my symptoms were almost exactly those of what is commonly called a stroke, and to be quite candid I thought for a moment or two that that was what had happened to me. My eyes were failing fast, and there is no doubt whatever that I was succumbing to a form of paralysis. I tried to shout in the hope that Roger was somewhere close at hand, but I couldn’t utter a sound. I tried to lift my arms, but they were as lifeless as leaden weights. And all the time the light was growing stronger. I must admit that at that stage I gave myself up for lost.

‘At that moment Roger walked through the door. I could just see him, faintly, through what appeared to be a deep purple mist that was rapidly closing in on me. He has since told me that it was broad daylight, so obviously my eyes were at fault. He also told me that I looked so dreadful that at first he thought I was dead. Then he saw the ray, and something more. He says he is convinced that he saw a shadowy form behind it. He still had the rifle in the crook of his arm but, of course, he had unloaded when he came into the house. Fortunately he still had some cartridges in his pocket, so he slipped one into the breach and let drive at the vague form behind the light.

‘I remember hearing the shot, but it was no louder than the crack of an eggshell. Then I lost consciousness. When I came round Roger was pouring some sal volatile between my lips. I could move, but only just. I seemed to have been stricken with chronic rheumatism in every limb. Well, to make a long story short, Roger got me to bed, and there I have been ever since, with Roger on guard. There is only one other point, but it is an interesting one. When Roger went back to the spot where he thought he had seen the figure he found something that supplied a real clue to what was going on.’

‘Bloodstains. There were bloodstains on the floor. A thin trail led to the door and out into the garden.’

‘Because in my limited experience I know that what can bleed can feel; and what can feel can be tackled with good honest powder and shot. If you had asked me to help you to keep a gang of spooks at bay, you wouldn’t have seen me for a cloud of dust and small pebbles. But the bloodstains make it a different proposition. From your accounts, these lads from the wide open spaces have some funny tricks, but if, as it seems, a lead slug can make a hole in one of them, then it shouldn’t be beyond our power to settle any argument to our own satisfaction.’ He turned to Maltenham. ‘Tell me,’ he said, ‘what happened to you tonight?’

‘I was the victim of a similar attack to that made on your uncle, but it was not so severe,’ replied the young earl. ‘You see, I felt I couldn’t keep awake indefinitely. While your uncle and I were fit we could take turns to mount guard, but with your uncle out of action it all fell on me. He saw I was cracking up under the strain, and suggested I should try to get in touch with you. I thought of the B.B.C., and went off to the village to telephone.

‘After I had rung them up I started off back, but was attacked in the drive by this infernal ray. I saw nobody, of course. When the light suddenly appeared in front of me I dashed into the wood and got hopelessly lost; as a matter of fact it was the lights of your car that gave me my bearings. I struck the drive near the house, but no sooner was I on it than I could feel—things—around me in the darkness. It was horrible. Then I saw the light again and I am afraid I panicked. I just sprinted for home for dear life. The ray followed me, and actually shone on me once; it produced a sort of numbing shock.’

‘Tonight, in the drive. The ray caught my arm and half paralysed it. It made me drop my revolver. It was not unlike an electric current shooting through my fingers.’

‘Well, what are you going to do about it?’ inquired Biggles. ‘You can’t go on like this indefinitely. Sooner or later something serious is bound to happen to one or the other of you.’

‘I’m afraid that’s only too true,’ admitted Dickpa. ‘I hate the idea of being run out of my own house by a lot of savages, but I think the sooner we find a place——’

There was a moment’s silence, and then the Professor nodded slowly. ‘I see what you mean,’ he said in a low voice. ‘You mean——’

‘I mean that people who have learned to control a deathray, or a ray that can produce paralysis, at the same time making themselves invisible, can hardly be classed as savages.’

‘There’s no other solution, bar a miracle, and miracles don’t happen nowadays. Obviously that fellow in your trunk was there all the time, but you couldn’t see him. You could see the weapon with which he proposed to kill you, and the bottle may have contained the dope that produced invisibility—we’ll call it that for want of a better name. That’s why the box was so heavy when the steward had to carry it. After death the fellow returned to normal form. Then again, the fellow in the room here. Malty says he saw a vague shadowy form—that’s right, isn’t it?’

‘Quite right,’ agreed Maltenham. ‘It was a spectral shape—the sort of thing one imagines a ghost to be.’

‘Yet the human body was there all the time; the presence of the blood proves that. Spooks don’t bleed—at least, I’ve never heard of one that did. But what nonsense am I talking?’ he concluded angrily. ‘We should have to believe in fairy tales to consider such things seriously.’

‘I don’t think so.’ It was the Professor who spoke. ‘I think you’ve spoken nothing less than the truth. I begin to suspect that the whole thing is far deeper and more sinister than we at first suspected. And after all, these people came from the Mountain of Light. Light! Mark the word. How can a mountain produce light? I’ll tell you what I think. I believe that this mountain exists, and that its remarkable properties can be attributed to large radium deposits. I’ve always had a half-formed idea in the back of my mind that such might be the case. Radium would account for the curative properties. Good heavens! why, nobody knows the full power of radium yet, and there’s no knowing what extraordinary things these people could do if they had radium in quantities. One grain is sufficient——’

‘Ginger,’ cried Biggles, springing to his feet, ‘have you been watching the drive?’

‘No; I am sorry, but I’m afraid I got carried away by the Professor’s story,’ admitted Ginger frankly.

‘I see,’ snapped Biggles. ‘Come on, Algy—and you, Ginger. You’d better come too, Malty. Our friends seem to be in a hurry,’ he added, as the knocking broke out afresh.

He ran quickly downstairs into the hall with the others close behind. ‘Maltenham, take the twelve-bore and post yourself at the foot of the stairs,’ he ordered. ‘Ginger, take the rifle and cover me.’ He picked up the elephant gun. ‘Algy, open the door and stand clear. I shall be interested to see the man who can take a left and right in the breadbasket from this baby and still stand on his feet,’ he added grimly. With the weapon at the ready, he took up a position about three yards from the door, facing it.

The massive oak door swung slowly inwards on its hinges. There was an instant’s silence, charged with tense expectancy, and then a short hysterical laugh broke from Biggles’s lips. The others stared in mute astonishment as a police-sergeant, followed by a constable, entered.

‘Why, what’s all this?’ asked the sergeant, looking from one to the other in amazement.

‘Friends!’ ejaculated the sergeant incredulously. ‘Is this how you usually greet your friends?’

‘Well, not exactly perhaps,’ replied Biggles rather lamely. ‘But what can we do for you, sergeant? You’ve come up about my car, I suppose?’

‘So it’s your car in the tree, is it?’ said the sergeant suspiciously. ‘Looks like you’ve had a close squeak, young man.’ He stroked his chin reflectively. ‘And it also looks to me as if you gentlemen have been having an evening on the spree,’ he added, winking significantly.

‘Is that what you’ve come here to tell us?’ inquired Biggles, rather coldly.

‘No, sir, it’s something much more serious than that,’ answered the sergeant quickly. ‘I’ve come to ask you if you can throw any light on this affair of the dead man that’s been found in the park.’

Biggles stared. ‘Dead man?’ he repeated foolishly. ‘No—but sit down, officer. Let me offer you some refreshment. Algy, close the door and bolt it. Maltenham, fetch the decanter and a couple of glasses.’ He laid the elephant gun on the table and sat down opposite the sergeant. ‘Now! what’s this about a dead man?’ he asked. ‘Who is it?’

‘That’s what we’re trying to find out. He’s a foreigner, though. Looks to me like a Chinaman, though the Inspector says he’s a Jap. Naked as a new-born babe, too, that’s the funny part of it.’

‘Shot. Shot right through the chest. A single gun-shot wound. The sort of hole you’d expect a rifle about that size to make,’ he observed slowly, pointing to the forty-four.

Biggles caught Maltenham’s eye and flickered an eyelid. ‘Who found the body?’ he asked.

‘Bert Dalton. Maybe you’ve heard of him. No? Ah, well, he’s a poacher. We know him all right. He was poaching when he found it. He don’t deny it. His story is that he stumbled on something in the dark, so he slips his torch across it to see what it was. He let out a yell, he says, when he saw it was a stiff ’un and made for the police-station as fast as his legs would carry him, which was the best thing he could have done. Lucky for him he’d only got his old twelve-bore, so we know he didn’t do the shooting.’

‘We took it to the mortuary, and then the Inspector suggested that it might be a good thing if I slipped along here to see if you knew anything about it.’

‘Funny. You’ve been doing a bit of shooting up here tonight, haven’t you? People don’t often shoot after dark—except people like Bert Dalton.’

‘Quite right,’ admitted Biggles. ‘But that was after he’d found the body, so we couldn’t have shot your man.’

‘Because I know exactly when Dalton found the body. I heard his yell of fright, although, of course, I didn’t know what it was then, or who it was.’

‘I see, sir,’ said the sergeant slowly. ‘No, I wasn’t suggesting you had anything to do with the shooting of this Chink, or whatever he is. The doctor says he’s been dead some time, twelve hours or more. The bullet was fired at pretty close range, he says.’

Biggles nodded. ‘Between you and me, sergeant, we’ve seen some funny people about in the park this last day or two; we thought they were gipsies. They may have fallen out amongst themselves. As you may know, Professor Bigglesworth, who, by the way, is my uncle, has been abroad, and there has been no one here to look after things, so people could pretty well come and go as they pleased on the estate. It might be a good thing if you had a thorough look round as soon as it gets daylight.’

‘I see, sir. Then we’ll leave him out of the proceedings if we can, but there’s bound to be an inquest, and he may be asked to attend.’

‘Very well, sergeant, you know best. And I’ll tell you what. While these strangers are about I should be glad if you would ask one of your men to have a look round here, say once a day, until further notice. Tell him to come up to the house to make sure everything is all right.’

‘Very good, sir, I’ll see if it can be arranged,’ agreed the sergeant, rising. ‘Good-night, sir.’

As the door closed behind the police officers Biggles looked at the others soberly. ‘Malty,’ he said, ‘I’m afraid you killed that cove.’

‘Nothing at present. Let’s get back to Dickpa and tell him what’s happened.’

They returned to the bedroom, where they told the Professor what had transpired.

‘Well, I’m getting tired,’ announced Biggles at last. ‘The point you’ve got to decide is, what are you going to do about this whole business?’

‘I don’t know how other people feel about it, but I know what I should like to do,’ replied the Professor.

‘Sounds crazy to me,’ observed Biggles. ‘You’re not by any chance thinking of asking me to fly you there, are you?’ he added suspiciously.

Biggles frowned, but there was a twinkle in his eye as he looked his uncle straight in the face. ‘Do you know, Dickpa,’ he said reproachfully, ‘I believe you’ve had that idea all along. Really, if you’d admit the truth, that’s why you sent for me.’

A faint smile spread over the Professor’s face. ‘You’re quite right,’ he admitted.

‘Do you realize what such an expedition would cost, quite apart from the risks?’ inquired Biggles.

Biggles swung round to face Maltenham. ‘So that’s it, is it!’ he observed. ‘You’re in the plot, too.’

‘I’m afraid I am,’ confessed Maltenham. ‘That is, I’m prepared to finance it, provided I can come.’

‘Yes, I’ve still got the old “Vandal”, but I don’t think she’s up to an affair of this sort. She’s obsolete, and the engine’s getting a bit shaky, which isn’t surprising considering the number of hours it’s done. No; if we went we should need a new machine.’

‘I suppose you know what sort you’d select, if you had to get one specially for this trip?’ inquired Maltenham.

Biggles thought for a moment. ‘Yes,’ he said, ‘there’d be no difficulty about that; but aeroplanes cost a lot of money, particularly amphibians, which is the type I should use, because we could then get down on either land or water in emergency.’

‘The machine, fuel, oil, and all the rest of the things we should need would leave no change out of thirty thousand pounds.’

‘Is that all? Then the matter becomes simple,’ declared Maltenham eagerly. ‘I have ten times that amount of money and nothing to do with it. I’m not concerned with making money out of this venture; the financial side doesn’t interest me. I’m only thinking about the good we might do. My governor always wanted me to do something big. He never had a very high opinion of me, and—well, I have a feeling that this is my opportunity.’

‘If I can be of some benefit to humanity I shall feel that I have done some good with my life.’

‘From what I can see of it, you’ll be lucky to have a life to do anything with by the time this business is finished,’ declared Biggles. ‘You’re thinking about the radium, of course?’

‘Nothing else. If it is there and we can get some of it, it may help to cure a million poor souls who are now dying of such ghastly diseases as cancer.’

‘Of course I’ll go,’ laughed Biggles. ‘To tell you the honest truth, I was hoping for something of the sort when I came here.’

‘You lie quiet and get yourself fit and well, Dickpa,’ Biggles told him seriously. ‘We can’t go until you’re on your feet again. And now where are we all going to sleep?’

‘The greatest danger we have to face is not finding a landing-ground when we get there,’ said Biggles seriously, looking at each of the four members of the party in turn as if seeking confirmation of his opinion.

Six weeks had passed since the S.O.S. message had sent the three airmen post-haste to Brendenhall Manor; they were now sitting on the veranda of the rest-house at Chittagong Aerodrome, which is situated near the frontiers of Bengal, Assam, and Burma. Nothing of importance had happened at Brendenhall after the departure of the police-sergeant. The Professor, as in duty bound, had attended the inquest on the dead native, and the others had escorted him to the court in a police car. After an interview with the Coroner, a non-committal verdict of ‘Death from Misadventure’ had been returned, and there the matter ended. Then the whole party had taken the next train to London without returning to the Hall, Dickpa deciding to leave the place in the hands of a competent agent rather than face the perils that unquestionably existed there.

In London they had sought out an obscure hotel, from where Biggles had quietly conducted the negotiations for the purchase of an aircraft and the preparations for the voyage. After considerable thought, and long and earnest debates with Algy, they had decided upon an all-metal, twin-engined ‘Gannet’ amphibian, one of a type that had recently gone into production for the Royal Air Force. It was, to all intents and purposes, a flying boat, but fitted with a wheel-landing chassis which could be raised or lowered at the will of the pilot. The two ‘Hercules’ air-cooled engines were mounted between the planes, one on either side of the hull, in accordance with orthodox design and practice. Forward were cockpits for two pilots sitting side by side, fully equipped with the latest ‘blind’ flying instruments. A low doorway gave access to the spacious cabin, which, besides having seating capacity for six passengers, contained roomy lockers for stores and equipment. These lockers were important; normally, in Service machines, they were intended for spare parts, in order that the machines could operate at sea as units independent of shore assistance, but they now formed handy receptacles for the compact stowage of the large quantity of food that the uncertain duration of the voyage demanded.

There had been some little trouble over ‘carnets’,—the document without which, in accordance with International Air Regulations, no aircraft may travel abroad—because naturally, Biggles found it difficult to state his destination. Ultimately he had overcome this obstacle by stating that the amphibian was bound for a pleasure cruise down the Australian route, but covered himself against the inquiries that would inevitably result when the aircraft ‘disappeared’, by saying that the party might make local excursions en route. He decided that if difficult questions were asked on their return to civilization, he would have to say that they had got off the track, or had been delayed at an out-of-the-way spot by bad weather.

Finally, the great day came when the Explorer—as the amphibian had been appropriately named—had left Brooklands on the first stage of her long journey. Thereafter they had followed the main trunk route to Karachi, across India, and then on to Chittagong, which had been selected as the jumping-off-place for the unknown, because it was the nearest aerodrome to their final destination. They had arrived on the previous day, and were now engaged in a last council of war.

‘Frankly, this question of finding a landing-ground is the only thing that worries me,’ continued Biggles. ‘You see, in the first place, it isn’t as though we knew exactly where we are going. We don’t, not to within a hundred miles or more. According to Dickpa’s field notes, read in conjunction with such maps of western China as exist, the distance to the approximate position of the mountain, in a straight line, is about eight hundred miles. By jettisoning some of our stores we could carry enough petrol in the tanks to fly there, look round, and if we found nothing, fly back. But I daren’t cut down the stores in case we do find something and want to stay there. Then again, it isn’t as if we had to fly over ordinary country. We’ve got to climb to fourteen or fifteen thousand feet to get over the mountains, and remain at that height over the plateau when we get there. This high altitude flying means loss of efficiency; it means that we shall have to fly most of the time on full throttle, or nearly full throttle, when at lower altitudes we should cruise on half-throttle; consequently, we shall want every drop of petrol we can carry to get up there and back. We’ve got to carry petrol with us, in drums, apart from what we can get in our tanks, including the extra tank I had installed. So we shall be all right as long as we can find a landing-place, because then we can go down, fill our tanks from the reserve supply, scrap the empty drums—which will be so much less weight to carry—and have a reasonably safe margin for getting back. But if we can’t find a landing-place we shan’t be able to refuel, in which case we may find ourselves in the cart. It boils down to this: we can’t get there and back without landing. I thought I’d better warn you.’

‘But surely we shall find a place big enough to land in, in all this vast country?’ put in the Professor.

‘Not necessarily. You said yourself that in all your journey on foot you did not see a single place that might be regarded as an aerodrome. A flat patch is no use if there are rocks and things sticking about. I for one don’t want to have to walk home; walking isn’t in my line: it’s too slow. Water is our best chance. If we can find a lake we shall be O.K., although we may have a job to take off at such a high altitude if the water is dead calm, as it is almost certain to be. In case you don’t know, a marine aircraft of any sort, but a flying boat especially, needs a wave to provide the kick that sends it into the air—particularly if it is heavily loaded, as we shall be. But there, it’s no use looking for trouble. As I said before, I thought I’d better tell you just how we stand, so that if any one thinks better of it there is still time to drop out.’

There was a chorus of protest and Biggles smiled. ‘That’s that, then,’ he observed. ‘We leave the ground tomorrow morning at the crack of dawn.’

‘How long will it take us to reach this place?’ asked Malty, as Maltenham was now called by every one.

‘Eight hours. I could do it in less, but I want to nurse my engines. We’ve got to go a long way up, remember.’

‘Absolutely on the top line ready for the word go,’ replied Biggles. ‘Algy and Ginger and I have spent the day looking over her, as you know.’

‘Very well, then I’m going to turn in. I am looking forward to tomorrow. I feel it will be one of the high spots in my life.’

‘In more senses than one,’ grinned Biggles, as the party rose to prepare for bed.

The stars were paling in an opal sky the following morning as the Explorer taxied out across the aerodrome into position to take off on her great adventure.

Biggles swung round slowly into the wind, eased the throttle open, and the amphibian raced across the sun-baked earth, leaving a swirling cloud of dust high in the air behind her. His face was set and grim, for the slightest swerve in such a heavily loaded machine might tear a wheel off, with disastrous results. The machine took a long run to ‘unstick,’ but once in the air she climbed steadily and smoothly, and Biggles brought her round gently on a course to the NNE.

Below them lay the virgin jungle, stretching away in all directions as far as the eye could see; away to the left, the distant delta of the Ganges lay like a skein of carelessly dropped grey threads. An hour passed, and the landscape remained unchanged except that straight in front a line of jagged white teeth now rose high into the sky like a mighty wall. It was a wall, in truth; a fourteen thousand feet high wall that through the ages has formed an impassable barrier across the neck of the Indian Peninsula, and held the Chinese hordes in check. In recent years one or two white men have made the journey from China to India on foot, but very few, and those that have got through have had little time to examine the inhospitable country on either side of them.

‘The best part of two hundred miles,’ replied Biggles tersely, easing back the joystick as he continued to climb for height in order to surmount the mighty range that lay athwart their path, at the same time watching the towering summits with brooding eyes, for he knew that, as in other mountains, mist forms easily and quickly in the Himalayas, and he had no desire to fly ‘blind’ through the menacing peaks.

The sun rose higher as the day wore on, but with the needle of the altimeter now on the fourteen thousand feet mark, they were too high to feel the heat. Below, the great Brahmaputra river wound a slow, sinuous course towards the Bay of Bengal, as if weary of the titanic struggle in which it had battered its way through the mountains, to fall at last through unfathomable gorges into the plains beneath.

The mountains seemed to be very close now, but Biggles, as his eyes probed the serrated edge for a pass, knew that they were still some distance away, and he continued to climb, glancing from time to time at his engine-revolution indicator. Slowly they drew nearer, and the details of the most awe-inspiring scenery in the world became visible; but Biggles gazed across the scene of stupendous grandeur unmoved. As far as he, as an airman, was concerned, the range was merely an obstacle that had to be overcome, a natural physical feature which he, by his skill and experience, must conquer. Nevertheless, a faint smile played around the corners of his mouth as he caught Algy’s eye after gazing down into a gorge that dropped sheer away below them to a point so deep that its bed was lost in dark, purple shadows. They were among the peaks now, tier after tier of them in a world of snow and ice, like sentinels guarding a new world.

The smile was suddenly replaced by a frown, however, as he caught sight of a white, wraith-like streamer curling away from one of the nearest peaks.

At first he thought it might be snow being blown away by the wind, but a second glance confirmed his suspicions. It was fog, and in a few moments several of the other peaks were half hidden. He looked around anxiously and saw that the mist was not coming from anywhere: it was forming on the mountains themselves; the very atmosphere was becoming opaque, due possibly to a sudden change in the temperature. He glanced to the right and saw that the sun had disappeared.

At that moment he was a good thousand feet above the highest peaks and flying on full throttle, so he eased the stick forward for more speed in the hope of getting clear of the mountains before the mist enshrouded them in its clammy folds. The machine roared on over the silent desolation, but one by one the peaks disappeared from view until only the nearest were visible, and they were but cold white spectres that loomed eerily in the gathering murk.

Biggles turned his eyes to his instruments. ‘Did you see anything ahead that looked as if it were above us?’ he shouted.

‘No, I think we’re over the highest,’ replied Algy, with an assurance he did not feel, for he knew that the lives of the whole party now rested on the engines. If either of them should fail, not all the skill and airmanship in the world could save them.

Biggles grunted and played for safety. Speed could not help them now, so he eased the throttle back a little and started to climb again, very, very slowly. At sixteen thousand feet he was satisfied that he was safe from striking an obstruction, but nevertheless he breathed a sigh of relief when a few minutes later the machine shot out into clear air under a steely blue sky. Below, the mist lay flat, like a white blanket of snow; to the east and west it stretched to the infinite distance, but a few miles ahead it broke off abruptly as if it had been cut with a knife. The phenomenon was not new to him, but he had never before observed it with so much satisfaction. ‘Pass me a sandwich, Algy, will you?’ he said. ‘I think the worst is over.’

And so it proved, for twenty minutes later the earth again came into view, and the white peril drifted away astern. ‘Thank goodness,’ he muttered thankfully, as he looked down with interest on a landscape that he knew had never before been looked upon by Europeans. It was not a pleasant sight. Grim, stark, and utterly lifeless, it was a land of tortured rock; of jagged knife-like ridges and deep forbidding gorges. ‘I hope there isn’t too much of this,’ he shouted, as he gazed below. ‘My goodness, did you ever see such a place! No wonder nobody’s ever tried to conquer the country.’

But his fears were groundless, for the rocky terrain slowly gave way to open plain, a vast wind-swept expanse of sand and shingle dotted here and there with sparse, grey-green herbage. ‘First one extreme and then the other. This looks like the world’s biggest aerodrome,’ observed Biggles, as he gazed across the monotonous waste.

For another two hours they flew on without change of scene. Once they passed a slowly moving line of men, driving heavy, bovine yaks, the animals that are used as beasts of burden on the great plateau; the men threw themselves on the ground as the machine sped over them. It was the first time either Biggles or Algy had seen natives behave in such a fashion, and the incident was sufficient to show that they had never seen an aeroplane before. They could see the details of the strange scene clearly, for although the altimeter registered fifteen thousand feet, Biggles reckoned that they were not more than a thousand feet above the ground. On another occasion they saw, in the distance, a small village of square, stone or mud houses, with thatched roofs; above it, on a slight rise in the ground, a large fort-like structure, built in the Chinese fashion with long overhanging eaves, appeared to be watching over it. They did not circle to examine it, but held on their course over the plain that was now giving way to broken country again. Low rocky hills appeared; they were divided by deep gorges, through which streams rushed in white-lashed pent-up torrents, while some distance ahead gaunt, grey peaks reared their heads far above the inhospitable vista. Beyond the peaks a great mass of rock rose in a series of steppes to a group of formidable mountains.

Biggles felt a sudden sense of disappointment. How on earth were they going to tell which one of them was the Mountain of Light—even supposing that the mountain they sought was in the group? The old saying, ‘looking for a needle in a haystack’, came into his mind. At home the difficulty had seemed trivial, but now, confronted by cold reality, the matter assumed a totally different aspect. Glancing at the watch on the instrument board, he saw that they had been in the air a few minutes less than eight hours. He beckoned to Algy. ‘Take over for a bit,’ he said. ‘I’m going to speak to Dickpa about landing. I don’t feel inclined to face that stuff ahead; we had better come down this side of it.’

Leaving Algy in charge, he went through into the cabin, where he found the three passengers gazing out of the window. The Professor and Malty were in earnest conversation, but they smiled when they saw him. He seated himself next to Dickpa and nodded towards the mountains. ‘I’m going to land this side of them,’ he shouted, above the noise of the engines. ‘We shall never find a landing-place amongst them, and goodness knows what is on the other side. We’ll fly up close to them, have a good look round, and then come down this side of them to refuel.’

‘You do whatever you think best,’ replied the Professor; ‘I leave things absolutely to you.’

‘All right; then that’s what I’ll do,’ answered Biggles; and then started as his practised ears detected a slight change in the note of the engines.

‘What’s the matter?’ asked Dickpa quickly, observing his startled expression.

‘Nothing, I hope,’ replied Biggles casually, but all the same he hurried back to the cockpit. One glance at Algy’s face was sufficient to tell him that something was wrong. Instinctively his eyes flew to the engine-revolution indicators, and he caught his breath sharply when he saw that the revs of both engines had fallen considerably. But the thing that astonished him most was the fact that both had fallen to precisely the same mark. For two engines to fail at the same moment would have been remarkable, but that they should both fall in equal ratio was an even more amazing coincidence. To his consternation he saw that both engines were still losing power, and what was more incredible, the needles of both indicators were falling in perfect unison. They might have been synchronized instead of being separate units. Never could he have imagined such a remarkable state of affairs, and he stared at Algy speechlessly, for once at a loss to know what to do.

Biggles shook his head. ‘Beats me,’ he replied tersely. ‘Let me have her: I’m going down.’ Curiously enough, neither of the engines appeared to be getting hot, and both oil and pressure gauges were registering normal figures.

He sat down in his seat, took over the joystick, and swung round in a wide circle in order to examine the whole area for the best place to effect a landing; but as he turned away from the mountains the roar of the engines increased in volume, and to his dumbfounded astonishment he saw both rev-counters climbing steadily. He shook his head like a man faced with a problem for which there is no answer, and turned back on his course with the intention of pursuing his original plan. Instantly both engines started to fail again, very slowly, but definitely. They reminded him of a gramophone motor running down. Quite bewildered, he turned away again with his eyes seeking a landing-place.

‘Am I going crazy or are they?’ he shouted to Algy, pointing at the instruments, the needles of which were now creeping back up the dials. In spite of the seriousness of their position, the expression on Algy’s face made him smile; never had he seen his partner so completely taken aback. ‘It’s no use,’ he continued, ‘we can’t go on like this. Something must be wrong; we’ll go down and see if we can find out what it is.’

They were now quite close to the nearest foothills, running along the face of a very steep escarpment from which a stream bubbled and spilt itself on to the plain. Below, the ground was flat, and as far as they could see free from rocks or other obstructions. There was little wind, if any, and with the idea of being as near to fresh water as possible, Biggles decided to land as close as he could to the cliff, in preference to the bleak open plateau, where moreover the machine would be exposed to the mercy of a gale should one arise.

He throttled back and flew low over the prospective landing-ground, subjecting every inch of it to a careful scrutiny before he attempted to land; then, satisfied that the ground was clear, he lowered his wheels and dropped lightly on the coarse grass and shingle that covered the earth at that spot.

A moment later the Explorer had run to a standstill; the roar of the engines ceased abruptly and was succeeded by an overpowering silence as he switched off and jumped to the ground. ‘Well,’ he observed, ‘we’re here, anyway.’

The door in the hull opened and the others stepped out, stretching their limbs after the long spell of enforced inactivity.

‘Well, so far so good,’ cried the Professor. ‘What is the programme, Biggles?’

‘First, all hands to refill the tanks, in case we have to get off in a hurry; second, we shall have to look over the engines; third, a square meal. I can do with one. We can talk about what we are going to do after that while we eat. It’s well on into the afternoon, so we shan’t be able to do much today, anyway. Come on, the sooner we get this spare petrol into the tanks, the happier I shall feel.’

Every one helped to get the drums out of the cabin on to the ground, and the spirit they contained was transferred to the tanks in an aluminium can. It was slow work, and it took them an hour to complete the task. The empty drums were then filled with shingle and placed under the wing-tips, to which they were attached by ropes, thus forming efficient anchors which would keep the machine steady should a high wind get up.

‘Good!’ exclaimed Biggles, examining their handiwork with satisfaction. ‘Nothing short of a typhoon will shift her now. Let’s have a look at these engines. Dickpa, I think you and Malty might be preparing lunch while the rest of us are doing that.’ He turned to where Algy and Ginger had already started an examination of the port engine.

‘Well, if there’s anything wrong with that, I don’t know what it is,’ declared Ginger half an hour later. ‘I’ve pulled these engines to bits and reassembled them in the workshops at Brooklands, and I think I know every nut and bolt in them. One thing is certain: if there is anything wrong, it will be a bench job to put it right.’

Biggles climbed off the plane on which he had been standing to examine the engine, and leaned against the leading edge. ‘I wonder,’ he mused.

‘I can’t get over the fact that both engines seemed to be affected simultaneously, and I was wondering if it could be anything here, any local conditions, that made them behave as they did. I’ve never heard of such a thing, but why the dickens should the two of them fluctuate like a single-power unit? They were both getting petrol all right, and lubrication seems to be O.K. If it had been one engine only I should have said it was something to do with ignition; magneto trouble, for instance. Could the mountain that we are looking for have any effect on them, or——’

Algy started. ‘It’s beyond me,’ he declared. ‘I know this, though. At our altitude it will take us all our time to get off if the engines won’t give their full revs.’

‘I was thinking that, but I fancy we shall be O.K. provided the trouble gets no worse. We shan’t have so much of a load to lift. We’ve only about two-thirds of our original petrol supply; and we could dump the stores in an emergency, reckoning on getting back to Chittagong in one hop.’

‘That’s true,’ admitted Algy. ‘But come on, lunch is on the table—or rather, on the grass. Hello, where’s Ginger?’

‘I’ve sent him for some water,’ replied Dickpa, nodding towards the stream that burbled a hundred yards or so away. ‘Hi! Ginger! Come on. What are you doing? We’re waiting,’ he called.

Ginger, who was walking up the stream, waved his hand to show that he had heard, but he continued walking upstream for a little way before he filled the can he was carrying and set off back towards the camp. The can he held in his right hand, but in the other, gripped between two sticks, was a dirty white object.

There was an expression of alarm and disgust on Ginger’s face as he strolled into the camp. ‘I had to go some way to get well above this thing,’ he explained. ‘I didn’t fancy water that came from anywhere near the place where I found it.’ He threw the white object on the ground with a shudder.

The others stared at it for a moment in silence, but the same expression was common to all their faces. It was loathing, for the white object was a dead centipede of huge proportions. Biggles thought it was the most repulsive object he had ever seen. It was about the size of a sausage, bloated in a disgusting way; its toad-like skin of fish-belly white glowed with a metallic lustre. Black, beady eyes glittered banefully, even in death; and from a cruel shark-like mouth protruded needle-like, incurved teeth.

‘For the love of Mike, don’t bring things like that into the camp, you little ass,’ snarled Biggles. ‘Gosh! what a horror. How do you expect any one to eat—ugh!’

The exclamation was accompanied by a violent shudder, and even the Professor turned pale. Ginger, evidently with the idea of removing the offensive reptile, had stabbed it with the end of one of the sticks he carried; instantly a stream of dark red blood gushed out, while the reptile collapsed like a pricked balloon.

‘If I step on one of those things by accident,’ said Biggles in a tense voice, ‘I shall have the screaming willies for the rest of my life. I hope they’re not common about here. If they are, then by the Lord Harry, the sooner I’m the other side of the Himalayas, the sooner I shall sleep o’ nights.’

‘And let’s get the grub round to the other side of the machine,’ suggested Algy. ‘That baby has an old-fashioned odour that doesn’t agree with my stomach.’

‘Nor mine,’ declared Malty, holding his handkerchief over his nose. ‘Goodness! what a shocking fug!’

Lunch was accordingly moved to a more salubrious spot, and under the press of healthy appetites the incident was soon forgotten.

‘What do you propose to do next, Biggles?’ asked Dickpa when they had finished.

‘I don’t think it’s any use thinking of flying today,’ replied Biggles. ‘I reckon we’ve got about enough petrol for two one-hour flights, and then we shall only have enough left to see us home. There is no point in staying here longer than is necessary, so I suggest that we take off first thing in the morning and try to locate the mountain. It’ll be a job, I’m afraid, unless there is a village or a town near it. We’ll decide what to do next when we’ve found it. I don’t think it’s any use making plans until we know how far away it is. In the meantime, as the air seems to be a bit nippy, I suggest that we unpack the tent and get everything fixed up for the night. At a pinch we could all get into the cabin, of course, but it would be a tight fit, and as we shouldn’t all be able to lie down it wouldn’t be very comfortable.’

‘I think that’s a good idea,’ agreed Dickpa. ‘We might as well be comfortable while we can.’

The tent was accordingly taken out of the machine and erected, while blankets, waterproof ground-sheets, small kit, and a supply of food were placed in it. While this was being done Biggles unloaded their complete armament, which consisted of a Lewis machine-gun, an express rifle, a twelve-bore double-barrelled gun, and two revolvers. The Lewis gun had been brought purely for defence, and while the rifle and sporting gun could be used for the same purpose, they were primarily intended to provide food for the pot if any game was found.

‘There doesn’t seem to be much to shoot at, does there?’ smiled the Professor, as he saw the weapons.

‘I never saw such a lifeless place,’ confessed Biggles. ‘Still, we may see something: one never knows. I’ll have a walk round presently.’

‘What about a good square meal presently and then turning in early?’ suggested Dickpa. ‘One uses up a lot of strength without knowing it in these high regions, and we shall want to be on the move early.’

This was agreed upon. Indeed, there was nothing else to do, for the sun, a fiery crimson ball, was already hanging low over the mountains. In spite of the chill in the air, the party in the tent soon developed into a picnic; a lamp was lighted and hung on the tent-pole, while the explorers clustered round a primus stove that had been set in the centre.

‘Well, I think it’s time we thought about turning in,’ said Dickpa at last. ‘Are you thinking of mounting a guard?’

‘Certainly,’ replied Biggles promptly. ‘We should be asking for trouble if we didn’t. I know we haven’t seen anybody about, but that doesn’t mean that the local gentry—if there are any—are unaware of our arrival. I don’t think there’s any necessity for you to do duty because you’re not really fit yet. The rest of us will do two-hour spells, times to be decided by lot in the usual way.’

The Professor insisted on taking his turn, however, although it was agreed that he should take the first watch which is generally reckoned to be the easiest.

‘Sentries will carry the twelve-bore and patrol between the machine and the tent,’ ordered Biggles. ‘A gun is better than a rifle in the dark. I’ll just go outside and see what the weather is doing.’ There was a moment’s pause, and then his voice, pitched in a queer tone, came from outside. ‘I say, come and look at this,’ he called.

There was something in his voice that sent the others scrambling through the narrow doorway into the open, but when they reached it they all stood still and stared in the direction of the mountains. It was a clear night, with a myriad stars glittering like diamonds in the frosty sky, but the moon was not yet up. Immediately above the mountains the sky was illuminated by a phosphorescent glow. It was not constant; it waxed and waned like the reflection of a colossal blast-furnace, but instead of being red it was a cold, vivid, electric blue. For some seconds they watched it in silence, all subdued by the unearthly manifestation.

‘It must be the Northern Lights—the Aurora Borealis. I’ve heard of them, but I’ve never seen them before,’ said Malty in an awed whisper.

‘I have, but they weren’t like that,’ muttered Biggles slowly. ‘It may sound a funny thing to say, but it wouldn’t surprise me if it is the reflection of the—thing—we’re looking for. The Mountain of Light.’

‘But it’s incredible,’ whispered the Professor. With the others he was strangely moved by the weird spectacle. ‘Why—why——’ He seemed to be at a loss for words.

‘I’m going up to the top of this scarp. It’s a fairly easy ascent a little farther along to the left, and from the top it ought to be possible to see over the panorama in the direction of the light.’

‘All right, then let’s all go,’ suggested Biggles. ‘The machine should come to no harm for the short time we shall be away; we shall be able to watch it, anyway.’

He fetched the lamp, but switched it off while its light was unnecessary, and without further delay the whole party set off quickly in the direction of the escarpment. It proved to be steeper than Biggles expected, but it was a fairly open ascent, without any involved rock climbing, and in twenty minutes, panting from their exertions in the rarefied atmosphere, they were within striking distance of the top. Unable to restrain their curiosity, they broke into a run, but as they breasted the final rise they all pulled up short, staring incredulously at the source of the phenomenon. No one spoke but Dickpa. ‘Great heavens!’ he gasped, and that was all.

At an indeterminable distance away in the heart of the mountains, a conical point of glowing blue light rose high into the heavens. The general effect was that of an iceberg, the top of which had been floodlit by lamps that alternated turquoise and violet, but infinitely more intense. At times it was so bright that the spellbound watchers had to shield their eyes, while at others it faded to a dull, purple glow. Only the very tip of the mountain was affected; what lay below it they could not tell, for in contrast to the brilliant radiance, the base of the mountain was an indistinct, shapeless black mass.

‘Well, there she is,’ said Biggles at last, in a voice that he strove to keep matter-of-fact.

‘Yes, there she is,’ repeated the Professor in an awed whisper. ‘There must be a tremendous amount of radium—if it is radium—in that mountain, to produce such an effect. At today’s value the man who owned it could buy the rest of the world.’

‘And perhaps cure half the suffering in the world,’ put in Malty in a voice that trembled. ‘What a sight to have lived to see. What a discovery! It will revolutionize—everything. Hello, what are you doing?’

Biggles had taken a small instrument from his pocket, and was squinting over it in the direction of the mountain. ‘It’s a pocket-compass, that’s all,’ he said. ‘I’m just marking her down so that we shall know her again tomorrow, in daylight, when the lights may not be working.’

‘Experience has taught me to take my bearings while they are apparent,’ replied Biggles sagely, as he closed the instrument and replaced it in his pocket.

‘It’s impossible to tell,’ answered Biggles, ‘but I should say it’s not less than four and not more than seven miles. One might easily be mistaken, though,’ he added guardedly.

For half an hour or more they sat on the hill and watched the amazing spectacle, entranced by its beauty, and it was the bitter cold that finally drove them back to the warm interior of the tent.

‘Well, I think we’ve done a good day’s work,’ observed Biggles as he unrolled his blankets. ‘We’ve got here and we’ve found the mountain. Tomorrow, with luck, we may stand on it.’

‘We might try to fly over and have a look at it from the air, but I have a feeling that if we are to reach that mountain we shall have to go on foot. In any case we can’t land on it, for obvious reasons, so if we want specimens of the rock we shall have to walk.’

‘Because I have an idea that that super-airway beacon is having some effect on my engines,’ replied Biggles slowly. ‘I shall know the truth tomorrow. If we can’t fly, then I imagine we shall walk. Having come so far it would be a pity to go back without taking a bit of Tibet rock as a souvenir. Well, we shall see. Call me when your watch is over, Dickpa. Good-night, everybody.’

At the first streak of dawn the following morning Biggles climbed into the cockpit of the Explorer and started the engines. He waited for a few minutes to allow them to warm up, and then, with the wheels chocked and with Ginger and Algy holding the tail down, he opened the throttle slowly. Twice he did this with his eyes on the revolution indicator. Then, leaving them ticking over, he jumped down to the ground.

‘It’s no use,’ he told the others. ‘Neither engine is giving more than three-quarter normal full revs. I can get her off, of course, but the lighter the load the easier it will be. I suggest you all remain where you are while I make a test flight; I’ll try to have a good look at the mountain at the same time.’

It was obviously the wisest plan, and although they were disappointed, the others agreed without demur. Biggles climbed back into his seat, the anchor ropes were released, the chocks pulled away, and the Explorer, after a long run over the uneven ground, roared into the air while the ground party watched it anxiously. They saw the amphibian fly some distance away, climbing slowly, turn back towards the mountain, and then resume its original course. Three times this occurred, after which the machine remained at a distance but climbed more swiftly.

‘I think they must be running all right now or she wouldn’t climb like that,’ observed Ginger critically.

The roar of the engines died away suddenly and the machine began a long glide back to its starting-point. Biggles made a clean, three-point landing, and taxied quickly to the spot where the others were waiting.

‘I’m certain I’m right about these engines,’ he declared. ‘They were as right as rain a few miles away, but the nearer I came to the mountains, the worse they got. Whether the thing is purely natural, that is, caused by mineral deposits affecting the ignition in some way, or whether we are being prevented from approaching by artificial means, such as a ray of some sort, is more than I can say. But it’s one or the other. The compass is useless; it swings like a catherine-wheel. I’ve seen one behave like that before, in a bad thunderstorm, when the atmosphere was charged with static electricity, but I’ve never known it affect an engine. I think to be on the safe side we’d better drop the idea of flying for the time being and try to reach the mountain on foot. It’s only about four miles away.’

‘Yes, there seemed to be a sort of dullish yellow area near the base, but I couldn’t make out what it was. I fancy it is a block of buildings; I know that sounds absurd, but I caught sight of flashes several times, as if the sun was shining on windows. I don’t know of any rock formation that could reflect light in quite the same way.’

‘Well, that doesn’t help us very much,’ murmured Dickpa. ‘No matter, let us try to get a closer view on the ground; we can’t have very far to go and the exercise will do us no harm.’

In a quarter of an hour they were ready to start. No guard was left with the machine because, as Biggles pointed out, if an attack was made on it, one man would not be able to do very much in the way of defence; consequently it was better for the party to stick together.

Biggles led the way, with the Express in the crook of his arm, while Algy, carrying the twelve-bore, brought up the rear. The others carried light loads of food and water in haversacks and water-bottles. They followed the bed of the stream along to the foot of the escarpment until they reached the point where the water fell down in a sheer waterfall from a point some two hundred feet above, but the place was unscalable, so they held on towards what appeared to be a fault in the rock; but when they reached it they found it was a narrow, evil-looking gorge that seemed to lead into the heart of the mountains. Automatically they turned their steps towards the entrance. Inside, the defile was strewn with boulders, some large and some small, while across the mouth they were piled one on top of the other in grotesque confusion.

‘This looks like a terminal moraine,’ observed Dickpa, half to himself, as he picked his way over the debris.

‘A what?’ inquired Biggles, looking carefully into the forbidding passage they were about to enter.

‘Moraine. This was a glacier not many years ago, I’ll warrant. Most of this country is of glacial formation; countless generations of slowly moving ice carved this cleft through the rocks. What a pity we can’t take some of those back with us; a horticulturist would cause a rare sensation in London with them.’ He pointed to a great drift of glorious blue gentians that sprawled over the rocks in several places, like patches of blue sky that had fallen down to earth.

‘You watch your step and never mind the posies,’ Biggles warned him, as a large rock on which he stood swayed dangerously. ‘We don’t want to have to carry you home.’

It was a curious place in which they found themselves, a dank depressing canyon that cut deeper and deeper into the heart of the rock until the sky was only a narrow blue slit far above.

‘One thing seems pretty certain,’ went on Biggles, ‘and that is that we shall have to come back the same way as we are going; I’d hate to have to try to scale these walls.’ He nodded towards the precipitous sides of the gorge. But presently it began to widen out, and although the ascent grew steeper, and remained very rocky, it was less gloomy.

In single file they tramped on, picking their way between great masses of grey, age-worn rock, and glancing furtively into the many caves that ran far back out of sight on either side. The vegetation had entirely disappeared except for sheets of grey-green moss, or lichen, that covered the rocks, sometimes hanging far over the sides in long streamers that swung to and fro fitfully in the cold breeze. From time to time they had to walk over pale, viscous-looking patches of slime that spread over the gravelly floor.

‘I wonder what makes this filthy stuff. Not exactly the sort of place to bring the kids for a picnic,’ observed Biggles, in a rather feeble attempt at humour.

‘Looks like the sort of stuff snails and slugs leave behind,’ ventured Ginger.

No one answered, and thereafter the conversation languished to mere monosyllables, and finally died away altogether. For no apparent reason their progress became slower; they seemed to have difficulty in lifting their feet; only Ginger went on with the same ease as before.

Biggles, who was still leading, suddenly pulled up dead. ‘Hello, that’s pretty,’ he observed, pointing to something that lay in their path. ‘It looks as if some one’s been up here before us.’

In the middle of the gorge lay a skeleton, a grim pile of whitened bones that did nothing to enliven the mournful scene. A few shreds of clothing still adhered to it, but it was too far gone in decay to give any clue to the identity of the lone traveller.

Presently they came to three more, lying in a huddled heap. Something bright not far away caught Biggles’s eye, and stooping down, he dug an object out of the shingle in which it was nearly buried. It was a silver cigarette case. Automatically he pressed the tiny fastener and opened it. Incised across the corner were some words. ‘To Grant, with love from Vera. Christmas 1901,’ he read aloud. ‘This was a white man,’ he said harshly. ‘A fellow named Grant evidently, although that was probably his Christian name.’

‘Grant,’ gasped Dickpa in a stifled whisper. ‘Why, that was Verdon’s Christian name—Sir Grant Verdon, the celebrated Asiatic explorer. He disappeared in western China, with two companions, in—let me see—it would be about nineteen-two or three. Nothing was ever heard of him. This, then, is the answer. Poor fellows; this is where they met their deaths. I——’

‘Let’s go on,’ put in Biggles tersely. ‘Too much of this sort of thing isn’t good for one.’

Suddenly the passage widened out into a circular arena-like basin with precipitous sides, but they could see the black slit that marked the continuation of the gorge on the far side of it.

‘Just a minute,’ called the Professor. ‘I’m afraid I shall have to rest for a bit. I’m fagged out; it must be the altitude.’

‘I’m not feeling so good myself,’ replied Biggles, in a curious voice. ‘My legs seem to have become sort of—heavy.’ He stopped and deliberately dragged the toe of his boot through the gravel. The trail was marked by a line of tiny blue sparks that crackled faintly, like a piece of tissue-paper when it is crumpled up. ‘I say,’ he went on in a startled voice, ‘look at this. I don’t like the look of it.’ With quite a natural movement, he placed the rifle against a large boulder that stood in the middle of the gorge. As the metal barrel touched the rock there was a blinding blue flash, and the cartridge in the breach exploded with a report that sounded like a thunderclap in the enclosed space. At the same time he was flung violently across the gorge and sprawled head-long on the ground. His face was pale as he slowly picked himself up.

‘No, thanks,’ replied Biggles in a strained voice, but he was obviously badly shaken. ‘I had a shock, that was all,’ he added. He put out his hand and leaned heavily against the wall to recover, but as he did so he started, and twisted as if in pain; he seemed to be making an effort to tear himself away.

Ginger dashed across, pulled him clear, and supported him while Biggles looked at his hand curiously; tiny sparks were running out of his finger-tips. He looked at the others in real alarm. ‘Don’t touch anything, anybody,’ he cried in a startled voice. ‘The place is bewitched. It’s electrified. Don’t move. Let us think. We must get out of this.’

The others were standing in a rough half-circle, watching him. ‘I’m dreadfully sorry,’ he continued in a strangely calm voice, ‘but I can hardly move. I’ve gone all—stiff. Algy—Malty, give me a hand.’ Algy tried to move forward to help him, but a cry broke from his lips and he looked at his legs helplessly. ‘They’re stuck,’ he said wonderingly.

Algy was staring across the open space with a look of horror on his ashen face. ‘I can see things,’ he stammered. ‘Shadows! Look, there’s one. What is it?’

Biggles turned his head slowly; his lips were parted slightly, showing his teeth. ‘If we’re going out, let’s go out with a bang,’ he snarled. ‘If you can see any one, shoot.’

Algy succeeded in getting the butt of the weapon to his shoulder, but he had not the power to raise the barrels, which sagged in his weakening grip.

Ginger, who alone seemed unaffected, sprang forward and caught the gun as it fell from Algy’s nerveless hands. Without hesitation he threw it up and blazed both barrels at something he could evidently see in the open.

‘I don’t know,’ replied Ginger grimly. ‘It seemed to be a sort of spirit—like a black ghost.’

‘I could see it, too,’ whispered Algy. ‘You got him, I tell you. He’s down. I saw him fall. Look!’ His voice rose to a shrill crescendo. ‘It’s taking shape—there—on the ground.’

‘It’s a man!’ cried Ginger hysterically, starting forward. ‘I’ve killed a man!’

‘Come back, you little fool!’ Biggles tried to shout, but the words were little more than a whisper. ‘Dickpa, what can we do?’ he asked.

‘Yes, what can we do?’ echoed Malty desperately. ‘I’m not afraid of dying, but——’

‘Who’s talking of dying?’ snapped Biggles, making a tremendous effort and turning towards the arena. ‘Ginger, come here.’

Ginger, who had run out into the open, but returned at Biggles’s command, hurried up to him. ‘Say! it’s a Chink,’ he whispered. ‘He’s yellow—and naked. I think I’ve killed him.’

‘He’s done his best to kill us,’ muttered Biggles. ‘Come here; what have you got on your feet?’

Ginger looked down and lifted up the sole of his shoe for Biggles’s inspection.

‘I thought so!’ There was a note of triumph in Biggles’s voice. ‘Dickpa! Ginger is the only one of us wearing rubber shoes. He’s insulated. Have we anything else made of rubber?’

‘Then he’ll have to fetch them,’ declared Biggles. ‘It’s our only chance. Ginger, run like a stag and fetch those sheets. If you fail, we’re sunk.’

Ginger set his teeth and glanced down the gloomy gorge. He flung the gun aside. ‘O.K., Chief,’ he said tersely, and dashed off like a sprinter in a race.

There was silence for some moments after he had gone. Then Biggles, walking stiffly, one step at a time, like a child learning to walk, managed to reach the gun. A little trail of blue sparks followed his dragging footsteps, while perspiration poured from his face at the mental and physical effort the movement required. ‘Algy,’ he said, ‘throw me some cartridges—if you can.’

Algy, with the ghastly deliberation of a slow-motion film, put his hand in his pocket and took out two rounds of ammunition. Making another stupendous effort, Biggles took them and loaded the gun.

‘How long will it—take him—to get—back?’ whispered Malty, obviously referring to Ginger.

Biggles pondered the question for a moment. ‘Between twenty and twenty-five minutes, I should say,’ he replied.

‘Queer business, this, isn’t it?’ went on Malty, his medical training asserting itself. ‘Symptoms of creeping paralysis; brain fairly active but the voluntary muscles lagging miles behind.’

‘Can’t we start working our way back—slowly?’ suggested Biggles. ‘Every yard may make a difference.’

With the exception of Dickpa they could still move by making an effort, but the Professor was too far gone. His eyes were open and he could still speak, but he had sunk down on the ground with his chin, held between his hands, resting on his knees. ‘This is how I felt—after the Blue Ray—at home,’ he breathed. ‘Go! Never mind me. Go!’

To carry him was an impossibility, so no one took any notice of his orders; another silence fell, and after a time his head sank forward.

‘He feels it worse, I suppose, because he has already had one attack,’ said Biggles, bitterly, turning his head to look at the body of the Chinaman now clearly visible about forty yards away in the arena.

‘What are you going to do when Ginger gets back with the sheets?’ asked Algy, forcing himself to be optimistic.

‘Get them under our feet,’ replied Biggles. ‘If we find they will insulate us we might go on.’

‘Great Scott! You’ve got a nerve,’ muttered Malty. ‘My one idea was to get back.’

‘I want to get back,’ Biggles told him soberly, ‘but my confounded curiosity won’t always let me do what I want to do.’

Biggles looked at his watch, but it had stopped. ‘Must be nearly twenty minutes. He should be back any time now,’ he answered. ‘That kid can run when he wants to.’ Slowly he turned his head again, and swaying unsteadily, tried to look down the gorge. But as his eyes passed over the dead Chinaman a movement beyond attracted his attention, and he half closed them in an effort to see more clearly. For some seconds he could not make out what it was.

On the far side of the arena yawned the black mouth of a cave, rather larger than any of those they had seen in the gorge. From it something appeared to be flowing, a dull white stream above which hung a pale blue mist. The movement was not regular, but undulating, like a shallow stream of milk flowing over a bed of large stones. It was coming in their direction, accompanied by a curious, faint crackling sound.

For some moments Biggles watched it wonderingly, and then as the awful truth burst upon him, his blood seemed to turn to ice. The expression on his face was sufficient to bring the others to their feet, sick though they were, although they would have sworn a moment before that such a thing was impossible.

‘It’s—centipedes,’ cried Algy, in a strangled voice, suddenly understanding. With a colossal and instinctive effort to escape, he forced himself round to face the backward path, but two dragging steps was sufficient to show that flight was out of the question. ‘What can we do?’ he cried, in a voice tense with horror.

‘It’s the first time in my life that I’ve had to admit it, but I don’t know,’ replied Biggles. ‘I couldn’t make ten yards, not even with those behind me. If Ginger is another three minutes I’m afraid he’ll be too late,’ he added in a voice that was strangely calm.

In that, however, he was mistaken. Two minutes later the leading ranks of the silver stream of death reached the dead Chinaman, and became a living whirlpool. Another two minutes and the serried ranks reformed and came on again. But of the Chinaman there was nothing left except a gaunt skeleton over which the noisome reptiles continued to pour.

Biggles raised the gun and pulled both triggers, aware of the futility of what he was doing. Bang! Bang! Two splashes of bright crimson showed for an instant against the white background, but they did not stem the tide, which poured on ever nearer.

They could see the reptiles now distinctly, as they surged over the ground in a sinuous rippling movement that began at the head and ran down to the tail. Their mouths were wide open, like hunting wolves; many were splashed with red stains that needed no explanation.

Biggles’s face was pale and grim. Algy’s eyes were wide open in a kind of fascinated horror, but Malty’s were closed, and he swayed on his feet.

The silver stream was not more than ten yards away when there came a shout from the gorge, and Biggles forced himself to turn. It was Ginger, panting, but running swiftly. Over his shoulder flopped a bundle of grey sheets.

‘Thank God,’ gasped Biggles. ‘Quick, Ginger, or we’re sunk,’ he called.

Ginger paused in his stride when he saw what was before him, but then came on again, his face as white as the silver stream.

‘Tear them in pieces,’ cried Biggles, striving to keep his voice steady. ‘Ah! you swine!’ One or two of the centipedes were well out in front of the others, but Ginger brought his heel down on them viciously. Then, with commendable presence of mind, he spread out two of the sheets on the ground and dragged Biggles and Algy on to them. The effect was instantaneous. It was as if an electric current had been turned off, leaving only a slight stiffness. They grabbed Dickpa and Malty and pulled them unceremoniously on to the sheets.

‘What is it?’ muttered Dickpa, opening his eyes. They fell on the silver stream.

‘Quick,’ snapped Biggles. ‘Tie the sheets round your feet—use your handkerchief—anything. That’s right.’

There were thirty seconds of something like panic, and then, snatching up the gun and what baggage they could reach, they set off down the gorge at a stumbling run with loose pieces of sheeting trailing from their feet.

For a hundred yards they ran without speaking, actuated solely by a unanimous desire to put as big a distance as possible between themselves and the creeping horror. Then Biggles glanced over his shoulder and slowed down. ‘Easy all,’ he said in a relieved voice. ‘We’re well ahead of them. Let’s get this footgear on a bit more securely; mine’s nearly off.’ They all bent down and fastened the strips of rubber sheet firmly over their boots, winding the ends far up their legs in the fashion of puttees.

Biggles finished first and looked back up the gorge. What he saw seemed to surprise him, for he took a pace or two nearer and continued staring. ‘Well, I’m dashed,’ he muttered. ‘What do you make of that?’ He pointed back in the direction from which they had come.

‘That! Those overgrown caterpillars. They’ve stopped; the whole lot of them. There’s not a movement. They look as if they were all dead. Well, if that doesn’t beat the band.’

They all stared back up the gorge with their eyes on the silver stream that appeared to have been frozen into an ice-drift. Not a ripple, not a movement, broke the sinister surface. As Biggles had said, every centipede might have been dead.

‘How very odd,’ observed the Professor in a mystified tone. ‘What on earth could have happened to them? One can understand them stopping when they saw we had disappeared, but surely some of them would still be moving.’

‘This excites my curiosity,’ declared Biggles. ‘I must have a closer look at it, or I shall spend the rest of my life wondering what happened.’

‘Come back, Biggles, you ass,’ cried Malty, as Biggles started walking back towards the motionless white tide.

‘Don’t worry; watch me run if they start off again,’ Biggles told him casually. ‘My gosh! there’s somebody there—look!’

At the same moment a loud cry of distress echoed eerily down the gorge. There was something so soul-stirringly hopeless, so dreadfully mournful in the cry that the explorers felt their heartstrings tighten.

‘He—lp! He—lp!’ came the voice again. It was followed by a whimpering sound like that made by a child when it is frightened.

‘Hark!’ Biggles stood transfixed, staring in the direction from which the sound had come. ‘Dickpa! Good heavens! It’s an Englishman,’ he cried incredulously. ‘There he is.’

The tiny figure of a man had appeared on the lip of the cliff on the opposite side of the crater, far beyond the still stationary centipedes. He ran to and fro and up and down in the last stages of despair, while from time to time he struck savagely at the air with what appeared to be a cudgel or club that he held in his hand.

Biggles caught his breath. He looked at the man and then at the silver stream. Then suddenly making up his mind, ‘A rescue,’ he called in a ringing voice. ‘Come on, Algy. Give me that gun—cartridges—thanks. Dickpa and Malty, you get back to the machine. Ginger, you go back too and stand by to start up.’ With that he was off up the gorge with Algy at his heels.

‘I believe they’re dead,’ he said, when they were only a few yards away from the nearest centipedes.

‘It certainly looks like it,’ admitted Algy, approaching warily. He put his foot out and touched one of them carefully with his rubber-bound boot. ‘Yes, they’re dead,’ he said, with a sigh of relief, as the centipede rolled over on to its back and lay still.

‘Come on, then,’ said Biggles, and clenching his teeth, he began squelching his way through the centipedes.

Algy shuddered violently as he followed. ‘Do you mind if I’m sick?’ he asked, in a stranded voice.

‘Not a bit,’ replied Biggles cheerfully, for with their inexplicable immobility, all fear of the centipedes had departed.

The lonely figure on the cliff saw them coming, and waved frantically. ‘Help! Make haste,’ he screamed, in a strong Scots accent.

The airmen broke into a run. They crossed the crater and presently stood at the foot of the cliff, on which the man was still fighting nothing more solid than thin air.

‘Mad as a hatter,’ observed Biggles. Then, lifting his voice, ‘Hi, how can we get up?’ he yelled.

‘Through the cave. Watch out for the blue light. It’s death,’ shouted the man.

‘Don’t we know it,’ growled Biggles, as he plunged into the yawning cavern, at the same time pulling out a box of matches. The stench was appalling, but he hurried on striking matches as he went. ‘Look,’ he gasped suddenly, and pulled up dead.

Algy stared over his shoulder in petrified astonishment. On their right, lighted by a brilliant electric bulb, was all the apparatus of a small, compact power-station. The light gleamed on a dynamo, bundles of cables, and a switchboard annotated with Chinese characters.

‘Come on, or we may be too late,’ went on Biggles. ‘We’ll look at this again when we come back.’ He hurried on up the swiftly rising floor towards the patch of blue sky that now appeared ahead. They had almost reached it when a beam of blue light stabbed the darkness from an opening on one side of them.

Biggles’s gun crashed as he fired from the hip. There was a sound of splintering glass and the light went out. ‘Keep going,’ he said abruptly. ‘I’m standing for no nonsense.’ As they dashed out into the open he staggered as if he had collided with some one. Turning swiftly with a snarl, he was just in time to see a shadow disappear into the mouth of the cave. Vague, indistinct forms flittered about the wide plateau on which they now found themselves. Most of them were concentrated round the man who, with his back to the edge of the cliff, was wielding a heavy iron bar like a flail. Every now and then there was a crash of breaking glass, and each time he let out a grunt of satisfaction. Queer high-pitched voices were calling in a strange language.

Again Biggles’s gun roared as he blazed both barrels in quick succession to the right and left of the lone fighter. Then, swinging the gun like a club, he plunged into the fray. The dark shapes backed away before him. ‘Keep it going, Jock,’ he yelled, with the fighting madness on him. ‘Come on, let’s get back through the tunnel.’

‘Ye can’t,’ panted the man, whom they now saw was very old, with a grey beard, and clad in heavy blue silk overalls.

Biggles, following the outstretched finger, staggered back. The centipedes were on the move again, pouring back into the tunnel. For a moment he was too stunned to say anything.

‘They’ve turned on the current again,’ explained the man briefly. ‘The bugs can’t move while the current is off; I turned it off myself. That’s why they came for me.’

The Scotsman turned towards the tunnel, and the others followed his eyes. Where the exit to the plateau had been was a solid wall of rock.

‘They will if we don’t do something about it, but I think I can stop them, though. What I make I can break.’ With this cryptic utterance, and carrying the iron bar, the man set off towards the rock door. On reaching it he paused for a moment to take a bottle from his pocket and pour some thick brownish liquid over his hands. Then, reaching up, he thrust the bar behind a black tube that connected the door with the solid rock, and, with a swift jerk, tore it clean out. There was a blinding blue flash as he did so, but he paid no attention to it. The door was in two parts, and after serving the other side in the same way, he stood back and surveyed his handiwork with a grim smile. ‘A’ weel,’ he said, ‘and that’s that. Those doors weigh twenty tons apiece,’ he observed, ‘so it’ll take them all their time to push them open.’

‘It’ll take us all our time to push them open, too,’ Biggles pointed out in alarm. ‘Is there any other way out of this place?’

‘Ye might have been in a worse one,’ nodded the man. ‘Come over here; let me show you something.’ He led the way across the plateau, which was nearly half a mile wide, to a point on the far side. ‘Look,’ he said, pointing.

About two miles away, but far below, was the camp. Through the thin air they could see it clearly with three tiny ant-like figures standing near the machine.

‘They might, if they knew where we were, and if the engines were running properly,’ smiled Biggles, a trifle sarcastically.

‘Because I’ve turned off the beam that was upsetting them; moreover, I’ve jammed the gear in such a way that it will take a day or two to put it right.’

Biggles stared. ‘This is getting beyond me,’ he complained bitterly. ‘I can’t compete with rays and blue lights and what not. I don’t know what things are coming to.’

‘You’ll know presently, if something isn’t done about it,’ the Scotsman informed him.

‘I’ll tell you later on. I’ve got to tell you—that’s why I’m here. I’ve only got about twelve hours to live.’

Biggles caught Algy’s eye with a look that said as plainly as words that he considered that the man was not right in his head. ‘I see,’ he said casually, looking back at the camp. ‘If we could signal to them, attract their attention in some way, and if the engines were all right, Ginger could fly up and fetch us,’ he mused.

‘A bonfire is about our only chance; let’s make a smoke-signal. If we can see them they ought to be able to see us; they’re certain to be looking this way. Come on, let’s make a pile of dry grass.’

Working quickly, they soon had a good heap of the coarse grass that covered the plateau, and putting a match to it, watched a tall pillar of white smoke rise upward. ‘I should think they are almost within earshot,’ said Biggles meditatively, and taking three cartridges from his pocket, he fired them into the air at regular intervals, the universal distress call.

With anxious eyes they watched the tiny distant figures. ‘Some one’s gone into the tent; I should say it’s Dickpa, gone to fetch his binoculars,’ said Biggles hopefully. ‘There he is back again. What did I tell you! Did you see the light flash on the lenses? He should be able to see us clearly.’ He whipped off his coat and waved it above his head.

‘Somebody’s gone to the machine; it’s Ginger, I expect,’ cried Algy excitedly. ‘Hark!’

From far away came the distant hum of the Explorer’s engines. They could see the light flashing on the spinning propellers.

‘You’re right,’ cried Biggles jubilantly. ‘He’s started up. I can see the others getting in.’

A few minutes later the Explorer began to move, slowly at first but with ever-increasing speed. Then, like a great white bird, it soared into the air.

‘He’s not taking any chances,’ went on Biggles, as the machine began to climb in the opposite direction. ‘Presently he’ll turn, and then he’ll discover that the engines are O.K.—that is, if they are O.K.,’ he added, with a sidelong look at the stranger.

‘It’s the first time I’ve ever seen one of those flying machines; aeroplanes you call them, I understand,’ said the Scotsman.

Biggles threw him an odd look. ‘Yes,’ he said. ‘With any luck you’ll soon be having a ride in one.’

Biggles did not answer. He was watching the amphibian turn in a wide circle and then head back towards the mountains. ‘Here he comes,’ he said. ‘Let’s throw some more grass on the fire to keep the smoke going. No rocks about, are there?’ He ran his eye quickly over the plateau, and saw with relief that it had a fairly level surface.

Swiftly, with the sun glinting on its silver wings, the Explorer sped towards them. It was soon evident that Ginger had seen them, for he shifted his course slightly, and throttling back, began an S turn to lose height and to come into the wind.

‘I’ll bet that kid’s perspiring with anxiety,’ muttered Biggles sympathetically. ‘So should I be if I were in his place, knowing that the lives of the whole party depended on a perfect landing. Steady, boy—gently does it—hold her off—that’s the stuff. Oh, nicely, nicely,’ he cried approvingly, as the amphibian flattened out and dropped her wheels gently on the tufty grass.

With a roar of her engines, the big machine swung round and taxied slowly towards them. They stopped as Ginger switched off; the door was flung open and Dickpa, with Malty close behind, jumped out, and ran towards the castaways. Ginger climbed down from the cockpit and followed them.

McAllister smiled faintly. ‘I dunno exactly, but I should say it must be close on fifty years ago.’

‘But—but you’re not more than fifty years of age now, surely,’ stammered Dickpa.

‘I was close on forty when they brought me here, and that was in 1885, or thereabouts, when I was wrecked in the China seas in the clipper Morning Star,’ answered the other simply.

‘You must tell us about it,’ declared Dickpa. ‘You’ll come back with us, of course?’

‘They—that is, the Chungs—know you’re there, and they can get at you. They know you’re here now, but they can’t get at you. Better stay here.’

‘Ay, I’ve bust the mechanism that works the door, and there’s no other way up.’

‘Nay, they can only move over specially prepared ground, and then when the current’s turned on. But give me a bite and sup. My time’s getting short and I’ve much to tell you.’

They returned to the machine, got out some provisions, and with the exception of Algy, who remained on guard, sat down under the broad wings of the aircraft.

‘What do you mean when you say your time’s getting short?’ asked Dickpa curiously.

In the light of the sinking sun Angus McAllister told his story, slowly and haltingly, like a man who speaks a language to which he is unaccustomed.

‘First of all,’ he began, ‘I must tell ye that I shall die soon after sunset; I’m telling ye that so that you’ll be prepared. It’s nothing mysterious. These people have inoculated me with a drug for so long that I’ve got to have it, or else—well, you know. That’s how they kept me prisoner. They didn’t need to put a guard on me. You see, if I’d run away I should have been dead before the day was out. So I had to stay to live. But I heard you were here, and I knew what would happen to you—as it has happened to other people—so I broke away and came to warn you.’

‘Ay, put it that way if ye like. But my time is up and overdue, so me life’ll be no great loss. I’m verra, verra weary. All the same, I should like to ha’ seen ma bonny Scotland once more—before I went. It’s been a long time.’ McAllister bowed his head and a tear crept down his lined cheek.

‘Wait a minute,’ cried Malty, springing up. ‘A drug, you say; what was it?’

‘Then I’ll see if I can find out,’ declared Malty. ‘There isn’t a drug without an antidote. Just a minute,’ he went on briskly. He ran back to the machine and presently reappeared with his medicine chest. He opened it, took out a case, and from a row of shining instruments selected a hypodermic syringe. ‘I’m going to take a blood test,’ he said. ‘Bare your arm, Mac; it won’t hurt.’

The old man rolled back his sleeve; he did not flicker an eyelid as the needle slid into a vein in his arm.

‘Good,’ said Malty in the true professional manner. ‘Now we’ll see what we can do about it. You go on with your story; the others can tell me about it afterwards.’ Picking up his case, he disappeared into the cabin.

‘As I was telling ye,’ continued McAllister, ‘that’s how they kept me prisoner. The Chinese pirates captured me way back in ’85, when I was wrecked in the China seas, me and the whole ship’s company. I was the chief engineer, and I fancy it was me they were after; the Chungs had told the pirates they wanted a man like me. The others they killed, every man jack of them, the murdering villains. They brought me here.’

‘I can tell ye, for I’ve lived so long amongst them that I know all about them, and their lingo. They’re the oldest race in the world, originally an off-shoot of one of the big Chinese mandarin families, thousands and thousands of years ago. The legend says there was a civil war in China, like there always has been; this lot got beaten and made for Tibet, and that’s how they discovered the mountain. I suppose you know about the mountain—I mean, that’s why you’re here?’

Dickpa nodded. ‘Yes, that’s why we’re here,’ he acknowledged. ‘But we really know very little about it. Is there any truth in this rumour about its curative properties?’

‘Maybe it’s the mountain, and maybe it’s something else, but I give you my word that I’ve never known anybody to be ill here.’

‘That they certainly do. In the end they just get infirm and die of sheer old age.’

‘Very pleasant,’ nodded Algy approvingly. ‘What do they do with the bodies?’

‘Cereals mostly. They don’t touch meat—not that there’s any here if they wanted it.’

‘What is this in the mountain?’ asked Dickpa. ‘We suppose it to be radium.’

‘Ay, that’s right, but it’s an unknown form—that is, unknown to any one except the Chungs—so I’ve heard them say. I haven’t time to go into all the details, but that mountain’s the greatest source of power in the world. There’s nothing else like it. If our modern engineers had it, it would supply the world with all it needs—motive power, light, heat, energy, everything. But these people are absolute fools in many respects. They don’t understand mechanical things, not really, and they never will—more’s the blessing. The old original crowd discovered the mountain, and set to work to harness it so that they could conquer the world. For a thousand years or more they worked, and were all ready to strike when the whole thing went wrong. No one knows what it was, but something blew up and they were nearly all wiped out. Pity they weren’t all wiped out, I say. It would have saved me a deal of trouble.

‘The few that were left started off again. Hundreds of years later they’d nearly got everything ready when it blew up again, mostly because they didn’t know how to handle the thing, I expect. There were a few left alive, but the old ambition was in them, and off they started again, which brings us to recent times. They found that the thing they needed was modern machinery, the stuff we make, instead of their own flimsy contrivances, to control the power properly, and they started buying it through China. Tons and tons of machine parts have been brought up on coolies’ backs from Shanghai.’

‘Ay, in the cave, I suppose. I assembled that for ’em. But let me go on. When they got the stuff they found they couldn’t erect it, and they needed a western engineer. So they got me, and made me work on the thing. I’ve spent my life at it, telling them what was needed, and putting the machines together when they came. Mind you, I didn’t know what they wanted it for, not then—not that it would have made much difference, I suppose.

‘When I’d been a prisoner about twenty years they captured another fellow, another engineer, an Irishman named O’Connor; but when he learned what the game was, he said he’d see them in Hades before he’d help them. So they showed him what they showed me—the centipedes. It didn’t make no difference, and in the end he was flung into the pit with them. Brave lad, he was. I hadn’t so much nerve and went on working.’

‘You said something about these devilish things being electrically controlled,’ suggested Biggles.

‘That’s right. They’ve got funny ideas, the Chungs—very peculiar ones. They don’t think as we do. They wanted some sort of defence for keeping inquisitive people out, so they worked their plans on their own lines. They don’t understand guns, or anything like that. The centipedes is one idea. Hundreds of years ago the scientists got to work—clever devils they are, too—and in the end, by hybridizing snakes and scorpions and all sorts of horrors, they produced a new sort of centipede. Poisonous, they were. But one day they all got loose and pretty near killed the whole colony before they were rounded up again. The Chungs saw that a weapon that could turn round and bite them wasn’t much use, so they started off afresh and produced a new lot. They’re not poisonous, but they just eat anybody alive by sheer numbers. All the same, odd ones were always escaping and the people got fed up with being bitten, so they started off on a new scheme. They produced a breed with funny sort of pads on their feet that could only move when the ground was electrified. Wherever they were, and whatever they were doing, they could paralyse the lot by a single switch.’

‘But how do the Chungs get about? Doesn’t this electricity in the ground affect them?’ inquired Dickpa.

‘It would, if they didn’t have a safety device. Inside every house is a pan of liquid, which is nothing more nor less than an insulating fluid. I used some just now when I disconnected that cable that controls the door to this place. If I hadn’t have had it on my hands I should have got a shock that would have burnt me to cinders. Everybody keeps a supply of it here. Every day they dip the soles of their feet and the palms of their hands in it, so that the current doesn’t affect them. It becomes a habit, just like washing. Then they discovered a new sort of ray: it shines blue. Whatever they turn that on becomes paralysed and then blind; presently they go mad and then they die. You want to look out for this ray, but the insulating varnish makes you proof against it, though.

‘The next thing they did was to produce a way of making themselves invisible. It’s a by-product of the stuff in the mountain that causes that, but it takes years of preparation to be able to do it. They take the stuff in the form of a liquid and it works the trick. You couldn’t do it; nor could I. It would kill us if we tried. The effect doesn’t last long, though. When they first take it you can’t see anything at all, but as it begins to work off you can see them coming round, so to speak, when they look like shadows. Those are the ones you two fellows saw when you first came up here. There were others you couldn’t see at all. When they’re like that they’re as brittle as glass, but they’re human enough, for all that, and you can smash ’em like so many bottles. And all the time these people are working to get hold of the world, and they’ll do it, too, unless some one steps in and stops them. Their plans are nearly ready.’

‘By radiating out in all directions from the mountains. As they go they will establish new stations and radiate again. They’ll send out rays in front of them all the time, which will clear the earth of every living thing for an area of hundreds of miles. The power will all be drawn from the mountain, picked up in the air without any wires or anything. An ordinary army is no use against that sort of thing. The whole British army could be wiped out at one click of a switch, and the fleet could be burnt up like so much matchwood. The discovery of aeroplanes upset them a bit because, for some reason or other, the power keeps low on the ground and they can’t get it to operate upwards—not very far. Still, they’re getting on, and they’re got to the stage when they can upset anything electrical. All aeroplanes have internal combustion engines, which need spark ignition in the cylinders to make them work, and the ray upsets the timing of the magnetos. The only way to stop it would be by painting the magnetos and the wiring system with this special varnish. It’s a perfect insulator; no ray can get through that.’

‘Yes, there’s quite a lot in my bottle. You can have it. Put it on your electrical gear, and your engines will be all right even if the ray is switched on. That’s done from the main control station, which is at the foot of the mountain. My word! you ought to see it. I doubt if there’s anything like it in Europe. Only a few people are allowed in. The head Chung, a fellow named Ho Ling Feng, is one. I’m another, but I’m watched pretty close. They take good care that I don’t get a chance to smash the works up. When you arrived on the scene every one got all excited, and they set about busting you up pretty quick. By a bit of luck and me, you’ve got away so far.’

‘Yes; I went mad, I think. I sloshed a bucket of varnish over the big dynamo so that the juice was cut down to about half power, or else you would have been dead, the lot of you, long ago; then, knowing about the centipedes, I ran down here and tried to jigger the machine that controlled them. But the party in charge of the station stopped me, though I managed to hold things up for a while. Then I ran up here to see if I could spot you; they followed me, of course, and the rest you know.’

‘If what you tell us is true, we must get back at once and inform the rest of the world what is going on,’ declared the Professor. ‘I doubt if they’ll believe it, though,’ he added plaintively.

‘A lot of use that would be in any case,’ snorted McAllister. ‘Suppose they did believe you, what could they do? Send an army? Even if they could get an army over the mountains, which I doubt, they’d be snuffed out before they could lift a rifle. Aeroplanes? You know what happened to your engines, and the power was only half on. On full power you’d have been down long before you got near this place. Air Force machines would be forced down in that wilderness of a plain, and then what could the fellows in them do? Nothing, except die of starvation, for there’s nothing to eat in this part of the world. If they brought food with them, they’d never get near here, not on foot; the rays and the centipedes would see to that—besides, you couldn’t expect ordinary generals, and ordinary soldiers, to fight something they can’t see. And in any case, they couldn’t do anything in a couple of weeks, and that’s the time I reckon the Chungs will start operations.’

The old man shrugged his shoulders. He looked suddenly very old and worn. ‘It’s up to you,’ he said simply. ‘You’ve got so far. No one has ever got so close before and never will again. You’ve got to smash the main power-station somehow. If you do that you’ll hold them up for years, and while they’re held up the people at home can get busy and do something about it. Well, that’s about the lot, I think, except that presently I’ll tell you all about the works and the lay-out of the place, so that you’ll know how things are fixed. I shall have to rest now; I feel all in.’

Malty ran out of the cabin with a test-tube in one hand and his case in the other. ‘I’ve got it, I’ve got it!’ he cried exultantly.

‘It’s a concoction of opium, that’s all,’ he went on. ‘I suspected it from the beginning, because opium is essentially a Chinese drug. I’ve mixed some dope that will kick it out of you. I’m afraid it may make you feel a bit queer at first, but I think it will work. I hope so, anyway. Come on, give me your arm and I’ll give you a dose.’ He took McAllister’s arm, inserted the needle, pressed the plunger home, and discharged the contents of the syringe.

The old man smiled wanly. ‘Maybe there’s a chance, you think?’ he asked wistfully.

‘I certainly do,’ declared Malty. ‘To tell you the truth, drugs happen to be a subject that I know a lot about—too much, I used to think.’ He caught Dickpa’s eye and winked.

‘I pray you’re right,’ muttered the old man feebly. ‘If it’s only to help you put an end to these devils. If you could do that and take me back in your aeroplane so that I could have one last look at the old Clyde—ah, but that’s too much to hope for.’ He sank back weakly. ‘I feel a bit queer,’ he murmured apologetically.

‘He’s all right,’ said Malty. ‘There’s no need for alarm. The stuff I gave him was bound to act that way; indeed, it would have been no use if it hadn’t.’

Biggles looked round and stretched. ‘Well,’ he said, ‘to come back to material things, what about a bit of food? Thank goodness we do at least know what it’s all about now. Afterwards we’ll see about knocking a few chunks off the Chungs.’

It was dark by the time McAllister had finished his story; they made him as comfortable as they could in the cabin, arranged for double guards over the machine, and prepared to turn in early. But they reckoned without the mountain, and the fact that they were now much nearer to it. As the sun sank an eerie light crept over the landscape, flooding everything with a ghastly blue luminosity. The peak was clearly visible from the plateau, and with their flying kit draped round their shoulders to keep out the cold, they sat and watched it for a long time.

‘No need for street lamps, with that thing burning,’ observed Biggles after a while. ‘It would get on my nerves. Whether it does good or not, personally I think it’s an unnatural horror that ought to be blown up. I wish we had a few hundred-and-twelve-pound bombs with us; we’d soon scatter their blinking beacon.’

‘Couldn’t one of us fly back and get some bombs?’ suggested Algy. ‘We could unload everything not required for the journey, which would allow for the weight and enable us to carry enough petrol to get back home again afterwards.’

‘And get clapped into jail for our pains. People don’t sell bombs, or give them away, without knowing what they’re wanted for. But we shall mighty soon have to be doing something.’

‘Because you can bet your life that the Chings, Changs, Chungs, or whatnot’s, are busy at this moment putting the works in order. When it’s running on full power again they’ll try to do something unpleasant to us—or to the machine. I don’t know about you, but I find this prospect of invisible rays tinkering with the engines a trifle unnerving.’

‘I know he does, and that may be so, but when I am flying I like to depend on something more substantial than a bottle of varnish. It doesn’t seem right. It would give a qualified ground engineer the jim-jams. No! I’ve got a feeling that we ought to get away from here before the Chungs get their works functioning again. Suppose the varnish didn’t work! A pretty lot of coots we should look, shouldn’t we, sitting up here with a whacking great aeroplane that wouldn’t fly, slowly dying of starvation!’

‘I think the sooner we get this varnish on the magnetos the better,’ said Algy. ‘It’s plenty light enough to see; what about it?’

It was nearly midnight by the time they had finished, for they had no brushes and were compelled to apply the varnish with their hands. It was slightly sticky, with a queer unpleasant smell, and Algy was bemoaning the fact that there was not enough water to wash when Malty came to tell them that McAllister had recovered consciousness.

‘Why wash your hands?’ asked Biggles as they went towards the cabin. ‘Let the stuff dry on; it may be useful. Do you remember how Mac poured it on his hands before he broke that connexion that worked the door? By the way it sparked, there was enough current there to burn him to a small piece of charcoal, yet he came to no harm. Hello, Mac,’ he went on as they entered the cabin.

The old man was lying on the floor with his head resting on a bundle of coats. He looked very old and frail, but his eyes were bright. ‘I’m still here,’ he smiled weakly.

‘Of course you are,’ Biggles told him cheerfully. ‘With Malty’s dope you’ll be skipping about like a two-year-old when we start knocking old Fe-Fi-Fo-Fum’s prize piece of furniture about.’

‘Don’t quite know; haven’t made any plans yet. To tell the truth, I was waiting for you to come round, to see if you could help us. If you can get on your pins, I’ll take you for a flight as soon as it’s daylight, and you can point out the works. If the worst comes to the worst, we’ll start dropping boulders on them, but we can’t make many trips or we shan’t have enough petrol to get home.’

‘Ay, that would be fine,’ said McAllister eagerly. ‘People who don’t want boulders dropping on them shouldn’t live in glass houses,’ he added, with a chuckle.

‘In the first place, the glass acts as an insulator; it’s got varnish with it; that’s what makes it yellow. In the second place, it keeps out the light at night, otherwise the Chungs would all go blind in time. That’s one of the effects of the light. The glass is as tough as steel, though, but if it snaps it flies to pieces. As a matter of fact, everything here is made of glass of one sort or another. You see, there’s no metal here except radium, but they can produce any quantity of glass quite simply by breaking down a small quantity of radium with rock. Granite, limestone, quartz, and so on, all produce a different kind of glass, which is used for its own particular purpose. I say glass, but it’s quite opaque—a kind of orange-yellow.’

‘But what’s our best plan of attack, do you think?’ asked Biggles. ‘How about machine-gunning them?’

‘You might break a lot of glass, but you wouldn’t do the works much harm.’

‘It would take more than boulders to destroy all the works unless you happened to hit a vital spot each time, which doesn’t seem likely,’ replied Mac doubtfully. ‘If you haven’t got much petrol, when you do do something you want to make a right job.’

‘Naturally. It’s no use killing a Chung or two. We’ve got to smoke out the whole nest. The question is, how are we going to do it? Maybe I shall get an idea in the morning, when I’ve had a dekko at the place from up topsides. Hello, what now?’

They all turned towards the door as Ginger, breathless and dishevelled, dashed in. ‘Say, Chief, something’s going on. These guys are trying to get the low-down on us.’

‘How many times have I told you to talk English?’ said Biggles shortly. ‘Where is it, and what’s happening?’

‘Over by the rock door. I thought I’d give the joint the once-over to see if there was anything doing. There’s a grinding noise inside. I think they’re trying to bore through the rock with a drill.’

‘The deuce they are!’ Biggles turned to McAllister. ‘Have these lads got any drills?’ he asked quickly.

‘Ay, that they have; I ought to have remembered that. They’ve got drills with radium-hardened points that will go through steel as if it were a piece of cheese.’

‘In that case it looks as if we’d better do something about it,’ replied Biggles. ‘You said something a little while ago about these fellows not understanding Western methods of fighting—guns, and that sort of thing.’

‘Well, it’s time they did. We don’t understand their weapons and they don’t understand ours, so that evens things up a bit. Let’s see if we can show them something. See you presently, Mac. Come on, chaps. You put that Lewis gun back in the machine when you took off, didn’t you, Ginger?’ he asked.

Biggles pulled out the weapon, clamped a drum of ammunition on it, gave a spare drum to each of the others, and led the way outside. ‘Don’t make a noise,’ he warned them. ‘I don’t suppose they can hear us, and we don’t want them to. Really, I don’t like this sort of thing, but in a case like this we can’t be choosers. Quietly now.’

They approached the rock stealthily, and then paused to listen. From inside the cave came a deep vibrating hum, and a rasping sound that was obviously the point of a drill biting into the hard, limestone rock of which the door was composed. Biggles located the sound, and bending down, listened intently. ‘They’re nearly through,’ he breathed, and moved the gun forward until the muzzle was in line with the spot.

‘I wonder what they’re going to do when they get a hole through,’ whispered Algy.

‘Whatever it is, it won’t be pleasant, you may be sure of that,’ Biggles told him tersely. ‘But we shall have something to say about it first, I hope.’

The grinding of the drill suddenly became a whirring scream, and then, almost before they were ready for it, a glowing metallic point, followed by a metal shaft of about the circumference of a half-crown, burst through the rock. For a few seconds it twisted and turned, apparently in order to make the hole larger, and then it was withdrawn.

As it disappeared from sight, Biggles pushed the muzzle of the machine-gun through the hole and pulled the trigger. Taka-taka-taka-taka-taka chattered the gun, the reports booming like a cannon inside the cave. There was a grim smile on Biggles’s face as he twisted the barrel from left to right in the same way as the drill had been turned a moment before. Fifty rounds or so he pumped into the cavern, and then withdrawing the barrel with a quick movement, stooped to listen. But no sound came through the hole. ‘They’re not saying much, but I don’t think they could have liked it,’ he said quietly, straightening his back, but keeping the gun at the ready. ‘Stand clear of that hole everybody. You never know: anything might come out of it, from centipedes to blue sparks.’

For twenty minutes or so they stood quite still, waiting for they knew not what, but not a sound of any sort came through the small aperture. ‘We seem to have discouraged them, at any rate,’ resumed Biggles. ‘All the same, we shall have to keep watch over this hole, which is a nuisance. I hate this cat-and-mouse game. I like to get a thing over and settled one way or the other. Who’ll take first watch? I want to go and have a word with the old man.’

Ginger volunteered, so leaving him on guard, the others returned to the machine. They found Dickpa and Malty a trifle agitated about the shooting, so they had to explain what had happened.

‘It always was, wasn’t it?’ replied Biggles harshly. ‘They started the rough stuff. All we wanted was to be friends and go home with a parcel of radium, which they could quite well have spared, anyway. Dash it, they’ve got a whole mountain of the stuff. It’s time we did a bit of attacking for a change; we’ve been on the defensive all the time so far, which isn’t right to my way of thinking.’ He went inside the cabin. ‘Hello, Mac, still alive, I see,’ he grinned.

‘That sounds like Ginger,’ muttered Biggles. ‘Now what’s the trouble, I wonder?’ He hurried to the door. ‘Yes, what is it?’ he called.

‘There’s a noise coming through the hole; I think it’s some one talking,’ yelled Ginger.

‘All right! Stand by; I’m coming,’ shouted Biggles. He turned to McAllister. ‘Are you well enough to walk, Mac?’ he asked.

‘You speak the lingo, don’t you? Will you come across and tell us what the Chungs are saying? Ginger thinks some one is talking through the hole—only thinks, mind you.’

McAllister smiled. ‘No wonder he only thinks,’ he said, getting laboriously to his feet. ‘These people don’t talk, they chirp.’

‘Well, come and do a bit of chirping,’ invited Biggles. ‘Algy, here a minute, and give us a hand.’

Between them they managed to get McAllister to the rock door, where Ginger was standing with the gun in his hands and his eyes on the hole.

Biggles stared. ‘Don’t tell me that’s a man talking,’ he gasped. ‘A fellow who could make a noise like that is capable of anything.’

But McAllister was making a similar noise, and the others looked on in amused astonishment as what was undoubtedly a conversation took place.

McAllister looked at Biggles. ‘They say that if we promise to go away at dawn, and never return, they won’t hurt us any more,’ he said.

‘What do they mean, hurt us any more? Tell them they flatter themselves; they haven’t hurt us yet. Nothing doing.’

Another conversation occurred, and again McAllister looked up. ‘Will you talk it over with Ho Ling Feng?’

‘No, sir. If Tingaling wants to talk to me, tell him to come and whisper through the keyhole. I don’t fancy my chance as centipede fodder.’

McAllister spoke again. ‘They say that if we don’t go they’ll paralyse us, and throw us alive to the centipedes,’ he said.

‘Well, you tell ’em to give the head lad my compliments and say that the first move he makes to give us the palsy we’ll come over and make his glass parlour look like a bottle merchant’s rubbish tip.’

McAllister gave the message, after which there was silence. ‘They’ve gone,’ he said.

‘They only wondered how I was still alive, and told me it was a pity I didn’t die as I should have done, because they’re going to make us die verra, verra slowly.’

‘You mean that’s what they hope. They appear to have overlooked the little detail about catching us first,’ observed Biggles casually, as, leaving Malty to keep guard over the hole, they turned towards the machine. As they walked slowly back towards it Biggles suddenly pulled up with a frown wrinkling his forehead. ‘By the way, Mac, what sort of a range has this ray got?’ he asked.

‘To tell the truth I’m not sure,’ replied McAllister, ‘but I think it’s a fair distance. Why?’

Biggles pointed to a peak that towered darkly far above them on the opposite side of the plateau. ‘That point is a lot higher than we are, which means that if these thugs can climb up it they’re likely to turn the spotlight on us from there, unless they’re bigger fools than I take them for. That hill can’t be more than a quarter of a mile away.’

‘Ay, that’s true,’ admitted McAllister slowly. ‘I never thought of that.’

‘Couldn’t it though! At that range it could. It would cause any metal in your machine to crystallize,’ was McAllister’s alarming reply. ‘In an hour or two the metal wouldn’t be any tougher than a biscuit; you’d be able to crumple it up like one. Is there any metal in your machine?’

Biggles stared at him horror-stricken. ‘Great goodness!’ he gasped. ‘Why, the machine’s all metal.’

‘Awkward! By the waxen sandals of Icarus, that’s putting it mildly. It will be more than awkward, believe me, if they turn the switch on. We’d better see about doing something before they do. An aircraft that you can crumble up like a biscuit isn’t my idea of a safe conveyance, not by a long chalk. Look! There you are! What did I tell you?’ He pointed to the mountain in question from which a dazzling blue beam had sprung. It fell on a point farther down the plateau, and began creeping slowly towards them.

Biggles grabbed the rifle that was leaning against the hull. ‘Give me a clip of cartridges, Dickpa,’ he said crisply.

‘It’s already loaded,’ the Professor told him. ‘What are you going to do?’

‘I’m going to try to douse the glim. It’s our only chance as far as I can see.’

‘You surely don’t think that you’ll be able to hit the operator, do you?’ asked Dickpa incredulously.

‘I don’t care what I hit as long as I put that light out,’ answered Biggles desperately. ‘The fellow who’s working the thing must be at the far end of the beam.’

‘Then I’ll make it dashed uncomfortable for him,’ swore Biggles. ‘Hey, Mac, what sort of an instrument discharges this ray?’

‘Then let’s see if we can give it a crack. I’d use the machine-gun, but it eats up too much ammunition, and we’ve only a limited supply. I shall have to use it, though, if this fails.’

The beam was perilously close as he walked quickly to the lip of the precipice, set the sights of the rifle at four hundred yards, threw himself flat, and snuggled the butt into his shoulder. He took careful aim and squeezed the trigger. There was a whip-like report; an orange flame, looking almost scarlet in the uncanny blue glow of the Mountain, leapt from the muzzle; but the light still blazed like an evil eye. Again he fired, but without arresting its progress. ‘Maybe it’s farther than I thought,’ he muttered, sliding the sight to the five hundred yards mark.

Twice more he fired without effect, but at the third shot the light swerved wildly and blazed down into the gorge. His cry of triumph was cut short, however, as it recovered and crept up to the plateau again.

‘That was my idea,’ Biggles told him grimly, as he took aim again. Five times he fired. At the fifth shot the light went out as if it had been switched off. ‘How’s that?’ he cried jubilantly.

‘Pass me that Lewis gun and don’t talk so much,’ ordered Biggles. ‘Ammunition or no ammunition, we’ve got to put that light out. We were fools to stay up here; we should have gone back to our first camp.’

‘ ’Twould have been the same thing,’ McAllister pointed out. ‘They could have got the ray on you anywhere on that plain.’

‘I suppose they could,’ admitted Biggles despondently. ‘In fact, the only safe place is in the air.’

‘Well, that’s out of the question. We haven’t enough petrol to cruise about indefinitely; we might as well go home as do that—better in fact. How are these things run—off a cable?’

‘Because these fellows that handle them are varnished from head to foot, in case of accidents. That’s the rule. People were always getting hurt.’

‘What we want is about a ton of varnish, enough to dope the machine all over,’ suggested Algy moodily.

‘And take a week doing it. A fat lot of good that would be. No, what we want is a howitzer, but as we haven’t got that either, why discuss it?’ Biggles trained the machine-gun on the light and was about to pull the trigger when he started back with a cry of dismay as two more beams sprang out from the hillside. ‘That’s done it,’ he muttered. ‘We can’t wipe out a whole blinking battery of ’em; we should use up all our ammunition inside ten minutes. How many of these confounded things have they got, Mac?’

‘Ay; those are the big ones they’re using. They’ve got thousands of little ones, pocket size, as you might say.’

‘They weigh a hundredweight or so apiece. It must take the Chungs all their time to get them up there; they’re not very strong. That’s why they’ve been so long getting them into position. I know that place they’re on; it’s a ledge beside the path that goes over the top. It would be too steep anywhere else.’

‘Ay, there’s a fault in the rock there; I’ve seen it on the way up to the dam, which is just over the other side of the hill.’

‘Ay, but it isn’t a natural one. There’s a two-hundred-foot dam built up across the gorge, to keep the water stored.’

Biggles thought swiftly. ‘This path you mention—do I understand it leads right over that mountain to the dam?’

Biggles nodded to where the first ray was now playing on the aeroplane. Another joined it, while the third began creeping searchingly over the plateau. ‘We’ve got to do something, and quickly,’ he snapped. ‘Frankly, I’d hate to try to land on smooth water in this tricky light, but I’d try it if I thought it would do any good. But by the time we got to it they’d have the light on us again from the other side of the hill, and we should be just as badly off as we are here—that’s so, isn’t it, Mac?’

‘We’ve one chance, then,’ said Biggles crisply. ‘Algy, get into that machine and taxi it about. You’ll have to play hide-and-seek with those rays until it’s light enough to fly without risking a crash. At the crack of dawn, take off and fly over to the lake. Ginger, get me that silk line, the one we brought in case we had to do any mountain climbing. There’s about three hundred feet of it. I nearly left it behind on account of the weight, but I’m glad I brought it now.’

‘There’s no alternative. Obviously, we can’t stay here, and we can’t cruise about because we haven’t enough petrol, so we’ve got to put the machine where they can’t get at it, and the only place within a hundred miles or so—according to Mac, and he should know—is on the lake.’

‘Don’t let’s argue,’ returned Biggles briefly. ‘Get this clear. I’m going to knock those thugs off that ridge. Then I shall hold the path till morning. As soon as it’s light Algy will bring the machine over to the lake and we’ll make contact. We shall have to go on holding the path, of course. Now I want you to lower me into the gorge and then send down the machine-gun. I’ve got a good chance, because that’s the last thing they’ll expect. Where does the path start from, Mac?’

‘You know where the gorge begins, on the far side of the crater, near the cave by which you came up to me this morning?’

‘About a quarter of a mile along there’s a break on the left-hand side. That’s it. Don’t go past it or you’ll find yourself in the town. Be careful; the path’s narrow in places, and if you slip you’ll fall a thousand feet before you hit the bottom. The ledge is about three-quarters of the way up, on the left. Don’t forget to varnish your feet and hands before you go, else if they turn the current on, you’ll be fixed, like you were this morning.’

‘I’m glad you thought of that,’ nodded Biggles. ‘Have you got that line, Ginger? That’s it. Now fetch me the bottle of varnish. Hi! where do you think you’re going?’ he added quickly, as Ginger began smearing the varnish over the soles of his boots.

‘I thought I might come with you. Two are better than one, because if one gets hurt, the other can help him, or carry on. Algy’s got to stay here to fly the machine, and if you go alone and get hurt, we’re all sunk.’

‘There’s something in that,’ admitted Biggles, ‘but it’s no job for a kid.’

Ginger frowned and made a pass with his hand. ‘Aw, cut out the kid stuff, Chief,’ he complained. ‘I’m the cat’s whiskers on a racket like this, you know that.’

‘Come on, then, let’s go. Algy, I’m leaving you in charge. I’m afraid you’ll be tired before daylight, but it can’t be helped. It’s funny, but I don’t feel in the least tired.’

‘You won’t, not up here,’ Mac told him. ‘You can go without sleep for weeks at a time; it’s something to do with the mountain.’

‘Then at least we’ve got something to be thankful for. From what I can see of it, we’re not going to have much time for shut-eye. Come on, all hands on the line.’

Biggles went down first, dangling like a spider on a web, pushing himself clear from the face of the cliff with hands and feet. It was an unnerving experience, and he breathed a sigh of relief as his feet touched the bottom. Ginger followed, after which the machine-gun and the twelve-bore were lowered. Then the line was drawn up again. Side by side the two airmen stood in the inky shadow of the gorge, listening, but all was quiet.

They crept along the foot of the cliff in single file until they neared the point where the gorge cut through the rock, and the cave of the centipedes yawned menacingly.

‘Keep your eyes skinned now: they’re about,’ breathed Biggles, as a faint monkey-like chatter came from the cave.

They dared not risk passing it closely, so they made a short detour into the crater, but always keeping in the shadow of the cliff, and with a watchful eye on the cave. Deep in its mysterious interior was a pale ethereal glow in which shadows flickered eerily. They passed on, however, and plunged into the gorge on the other side. Far above them the blue beams, now four in number, cut glowing fingers of light through the air, like neon street signs seen through a fog.

The sudden roar of the Explorer’s engines made them jump, but then, remembering the reason, they smiled at each other. ‘That’s Algy starting his merry-go-round on the plateau,’ whispered Biggles. ‘Ssh! I believe some one is coming.’ From some little distance up the gorge came the crunch of pebbles as they were trodden underfoot by swiftly striding steps.

The airmen crept behind a buttress of rock and waited, hardly daring to breathe. Nearer and nearer came the footsteps. Biggles set the Lewis gun against the side of the cliff and picked up a loose piece of rock. ‘There must be no noise,’ he muttered. Then, suddenly, the footsteps were right on top of them, and a dark figure loomed in sight. They had a fleeting glimpse of a flowing robe, a pale face with pronounced, slanting eyes and high cheek-bones, and then the man had passed swiftly on, looking neither to right nor to left in his haste. Biggles waited until he had disappeared round the bend and then squeezed Ginger’s arm. Together they set off again, stopping every few yards to listen.

Neither of them ever forgot that walk in the deep, sombre canyon, with the silent but potent rays above, and every shadow a menace.

‘We must be getting near the path,’ whispered Biggles, as he peeped round a bend, and then sprang back with an exclamation he could not stifle.

Ginger, who was close behind, caught sight of a monstrous figure that barred their path; the body was in shadow, but high above the light of the mountain reflected dully on a broad, bestial face that gazed down the gorge with a fixed, unchanging leer.

Biggles moistened his lips and passed his hand over his forehead. ‘Gosh! that gave me a fright,’ he said quietly. ‘Mac should have warned us about that.’

‘It’s a statue, or an idol, by the look of it,’ replied Biggles. ‘Thank goodness it isn’t human.’

They passed the foot of the monster hurriedly, for there was something terrifying in its sphinx-like stillness, and came upon the path almost at once. For a moment or two they looked at it doubtfully, for it was no more than a narrow crack in the rock as if the very mountain had been split by a mighty upheaval of the earth. The path was, in fact, a fissure in the rock, about three feet wide at the entrance, although what lay inside they could not tell, for it was as black as pitch.

‘Looks like the original dragon’s lair,’ grumbled Biggles, as he took a tentative step forward, feeling his way carefully with the muzzle of the gun.

For a distance of fifty yards or so they crept on, step by step, keeping their balance only by groping along the wall and watching the pale slit of starry sky above, and then they came to a hairpin bend. ‘Thank goodness the path broadens a little farther on,’ Biggles whispered, as he saw a large patch of sky some distance ahead.

‘If we meet anybody here there’ll be no hiding,’ breathed Ginger; ‘we couldn’t pass without touching.’

‘In that case it will be up to us to touch them first—with a brick,’ Biggles told him grimly. ‘We mustn’t start shooting down here and alarm the people up top if we can possibly prevent it.’ He reached the starlit area and paused, peering in uncertainly to left and right, for the rock walls had terminated abruptly, although there seemed to be a dark shadow on the right. Puzzled, he picked up a pebble and tossed it, and then held his breath as no answering sound came. Several seconds later a distant rattle echoed far, far below. ‘My word! what a hole,’ he gasped. ‘We shall have to be careful; I nearly walked into it. Can you see the path?’

‘That’s it, straight ahead, isn’t it?’ said Ginger softly. ‘It looks to me like a narrow bridge with a sheer drop on either side.’

‘I believe you’re right,’ answered Biggles quietly. ‘I don’t think much of this.’

They moved slowly forward again, testing their weight at each step before taking the next, and emerged on to a bridge of such breath-taking horror that Biggles, accustomed to looking down from great altitudes, hung back and broke into a perspiration. It was not more than eighteen inches wide, with no parapet; on either side stretched an inky void. Whether the bridge was artificial, or a natural razor-backed ridge, they could not see; nor did they delay to find out, but crawled across it with more haste than elegance. On the far side, on the right, the rock rose sheer again, but the precipice remained on the left, and the path became nothing more than a narrow cornice cut in the side of the living rock. In places the wall overhung them, so that they appeared to be walking through a tunnel from which one side had been removed.

Ginger glanced back over his shoulder, and touched Biggles lightly on the arm. ‘Look!’ he said softly.

Biggles turned. So close as to appear within hailing distance was the plateau; even as they looked they saw the Explorer pass swiftly through one of the rays as Algy taxied to and fro in an effort to avoid them. ‘I hope he doesn’t make a mistake in the dark and go over the cliff,’ he muttered with a worried frown. ‘Let’s go on.’

They continued on their way, and the next bend brought them to within sight of their objective, although as yet they could see nothing except the point from which the rays sprang. They were moving on again when suddenly there came a faint chink of metal striking against rock a little way in front. Biggles pulled up dead, peering up the path. ‘There’s somebody just in front of us,’ he breathed. ‘Looks like two or three men carrying a pole. They must be Chungs taking up another ray-thrower—or whatever they call the thing—but I can’t see very clearly. This confounded light is deceiving. There is this about it, though: if the people on top see us coming, maybe they’ll take us for another crew of ray experts. Never mind—let’s keep going.’

Another fifty paces and the general outline of the place became clear. The path wound upwards to the summit which, bathed in the glow of the mountain, still towered above them. Some little distance below it a fairly wide ledge, such as McAllister had described, formed a flat shelf in the side of the rock. On it a large number of men were clustered, in groups, and from the centres of the groups sprang the destroying rays. Another point of interest was the fact that the actual summit commanded the shelf. Below and behind them lay the plateau on which the amphibian still pursued her earth-bound course.

But for the imminent destruction of the machine, Biggles would have preferred to have gone straight to the summit and held the pass simply in order to prevent the enemy from overlooking the lake, but the immediate peril demanded more urgent action. ‘I’m afraid it’s going to be war, Ginger,’ he said quietly. ‘I can’t warn the blighters to clear out because I don’t know the lingo, but we’ll give them a chance. If they try any funny stuff, though, they’ll go down the hill faster than they came up. When we reach that next rock there’ll be no more cover, but we shall be within fifty yards of them. We must keep going until we get on the top side of them, so that whatever happens we can make the summit. If they spot us, and attempt to get a beam on us, let drive with both barrels and make a dash for the path beyond the ledge; then re-load and shoot again if necessary. If they don’t spot us, hold your fire and leave it to me.’

But to hope to escape detection in the bright light of the mountain was hoping too much, as events showed. They had, it is true, almost reached the spot where the ledge branched off from the path, when a shrill cry of alarm, quickly followed by others, rang out from the clustered groups. Simultaneously the nearest ray swung round in a flashing arc towards them.

‘Come on,’ yelled Biggles, throwing aside any further attempt at concealment, and suiting the action to the words, he dashed up the path with Ginger hard on his heels.

That they would reach and pass the turning before the figures on the ledge could intercept them was almost certain, but they had reckoned without the small party of Chungs who had immediately preceded them up the path. Biggles had, in fact, forgotten them, being under the impression that they had joined the main party, whereas they were actually resting in the shadow of a mass of rock that marked the junction of the path and the ledge. His first intimation of their presence was a miniature ray that stabbed through the darkness towards him; it struck him on the knee with the dull force of a mallet blow, and nearly brought him down. He stumbled under the shock, and the heavy gun flew out of his hands. A second ray leapt towards him and he twisted like an eel to avoid it. At the same instant he was almost deafened by the roar of Ginger’s gun almost in his ear.

Ginger, to whom the whole thing had been apparent, realizing the desperateness of the situation, had fired over Biggles’s shoulder, and that some of the shot had found its mark was instantly apparent. One of the two rays went out and the other fell to the ground, where it flickered harmlessly on the rock.

The whole thing had only occupied perhaps three seconds, and by the time the two small rays had been put out of action Biggles had recovered his balance and snatched up his gun; but as he did so two Chungs loomed darkly on the path and were on him before he could find the trigger. Instinctively using the muzzle of the gun as a bayonet, he lunged at the first, caught him in the pit of the stomach and sent him hurtling into space; but the second clutched the barrel and clung to it desperately. For a moment it looked as if Biggles would have to release his grip on the gun or go over the cliff with it, for the Chung threw all his weight on it, and having the advantage of the rising ground, forced him backwards towards the chasm.

Ginger was momentarily helpless, for being behind Biggles on the narrow path, he dare not shoot for fear of hitting him; but finally, seeing that only desperate measures could save them, he flung himself flat and fired upwards through Biggles’s legs. Instantly the strain on the gun relaxed as the Chung collapsed, and in the suddenness of the relief, Biggles nearly fell the other way. ‘Good work,’ he panted as he recovered, and threw a swift glance at the ledge. To his horror he saw that the whole crowd of Chungs were pouring along it towards the junction, which they had almost reached. They appeared to be figures of fire, for one of the big rays was now blazing straight along the ledge towards the path. ‘We’ve got to get above them or we’re lost,’ was the thought that flashed into his mind, and without waiting to see what Ginger was doing, he dashed forward. Ten yards from the junction he saw that the Chungs would reach it first, so he played his trump card. Sinking down on to his knee and resting the barrel of the gun on a convenient rock, he pulled the trigger and raked the ledge with a stream of lead.

The result was instantaneous. All the rays went out except one, which disappeared over the cliff, to reappear a moment later, a whirling beam of light that flashed alternately on earth and sky as it turned slowly over and over on its long plunge to oblivion. Several of the Chungs fell, and the foremost started back in a frantic attempt to get out of the hail of bullets. This gave Biggles the brief respite he needed. ‘Come on,’ he yelled, as he leapt to his feet and raced past the critical point. He was round in a flash, looking anxiously for Ginger, and was relieved to see him following, but still some distance down the path. ‘Quick,’ he yelled as he saw the Chungs coming on again, but he stopped them with another burst of fire.

‘That guy—wasn’t dead. Got me by the foot,’ panted Ginger, as he ran up.

‘Re-load, but don’t fire except at rays unless I give the word,’ snapped Biggles. ‘Shoot at rays on sight. We seem to have got ’em rattled,’ he went on, covering the Chungs who were now milling about in the wildest disorder. ‘They daren’t pass us, and they can’t go the other way because the place is a cul-de-sac. We’ve got ’em cold, but it’s no use wasting ammunition if they’re beaten. Let’s move a bit higher up and give them a chance to get out.’ They ran a few yards farther along the path and took up a fresh position.

The Chungs evidently saw them go, for as if seized by a common impulse, they poured along the ledge towards the path.

‘All right, let ’em go; don’t shoot,’ cried Biggles as Ginger fidgeted with his gun. ‘They’re running,—not attacking.’

The rout became a stampede. Like a herd of animals the Chungs swept past the airmen and raced down the path, pushing each other over the precipice in their blind panic. Biggles fired a few rounds over their heads to speed them on their way, and then, satisfied that the ledge had been evacuated, he turned and hurried on towards the summit. ‘These are the people who are going to rule the world,’ he muttered, as they ran on. ‘If they do, it won’t be by courage, but by a weapon which nature has placed in their hands. Here! what the dickens are you doing?’ he exclaimed, as there was a flash and a report, and a green signal light zoomed upwards into the sky.

‘Algy gave me the Very pistol just as I was going, and asked me to fire a green light if we managed to get to the top. He was a bit worried about us. He knows now that we are all right. There you are,’ he continued, as the drone of the Explorer’s engines died away, and the vibrant hum to which they had become accustomed was replaced by a deathly silence.

A few more steps and they were on the summit, with what appeared to be the whole world at their feet. The scene was so indescribably beautiful that even Biggles held his breath. On their right the Mountain of Light pointed a glowing finger of blue fire towards the starlit heavens, its uncanny radiance reflecting on a hundred peaks that stretched away, one behind the other, until they were lost in the vague horizon. Before them lay the lake, a vast, motionless pool of liquid fire, around which, at intervals, the pinnacle-like peaks stood like grim sentinels. It was as motionless as a sheet of ice, and looked as cold. On the other side lay the open plain, a sombre shadow that reached to the infinite distance, while below, surrounded by the yawning gorge, was the shadowy outline of the plateau.

Silence hung over everything; not the silence of civilized countries, but a deep, breath-taking silence, a complete absence of sound that worried the ear-drums. Of it was born an atmosphere of unutterable loneliness, and Biggles shivered suddenly. ‘I’m glad you came, laddie,’ he admitted. ‘This is no sort of place to be alone. Makes one feel kind of—small. My word! isn’t it perishing cold! I’d feel like lighting a fire if there was anything to burn. Never mind; we’re here, that’s the main thing. Let’s get the gun fixed to command the path. Thank goodness it must be nearly morning.’

Their teeth were chattering with cold by the time a pale glow in the east announced the birth of another day. Slowly the false dawn faded and was replaced by the flashing shafts of light of the rising sun. As the light grew stronger the Mountain of Light waned slowly, and presently gleamed pink against a sky of eggshell blue. Below, the plateau was still shrouded in purple shadows, in which the gorge stood out clearly as a cold-black slit in the earth.

‘They shouldn’t be long now,’ muttered Biggles, as he turned away from the rosy peaks to stare down at the plateau. ‘I should have thought they’d have started up before this,’ he added, with a trace of anxiety in his voice.

Another five minutes passed slowly; the light began to creep into the valleys, and Ginger stirred uncomfortably. ‘Yes,’ he said slowly, ‘it’s time Algy was moving. I expected they’d be here by now.’

The rim of the sun crept up above the jagged peaks, and as if a curtain had been drawn aside, the plateau was flooded with light. Neither Biggles nor Ginger spoke. They just stared down at the gleaming white wings of the Explorer and a crowd of blue-robed figures that surged about it. A full minute ticked by.

‘Ye-s. They’re Chungs all right,’ agreed Ginger bitterly. ‘How did it happen, I wonder.’

‘No use wondering,’ answered Biggles briefly. ‘It looks like a bad business to me. Well, it’s no use sitting here any longer.’

‘Frankly, Ginger, I can only think of one thing,’ replied Biggles. ‘To sit here and slowly starve or freeze to death is not my idea of a happy ending. Neither does the prospect of starting to walk back to India, without the others, even if we could, make any great appeal. So if you’re agreeable, I suggest that we walk down the path, shooting every thug we meet, until something stops us. If we can reach the cave and re-take the machine, so much the better; we’ll make that our objective, so to speak. If we do manage to get it, then we’ll proceed to drop boulders on Chungville, or whatever they call their precious town, until there’s no petrol left in the tanks. By which time there should be plenty of work down below for the local glaziers. How does that strike you?’

‘Good enough! Then let’s start. Shoot at anything and anybody. If they want a rough house, then, by gosh, they can have it!’ Biggles rose to his feet and examined his gun carefully. ‘How many cartridges have you got for that blunderbuss of yours?’ he asked.

‘Fine. Try and make every round count. The more Chungs we can fill—hello, what’s that?’ Biggles spun round as an unmistakable rifle shot crashed somewhere far below. Bang—bang . . . bang . . . bang, spat the rifle yet again.

Biggles’s hands were trembling slightly as he stared down the path. ‘That’s the Express; the magazine holds five rounds,’ he snapped. ‘And that’s Algy shooting; none of the others would fire at that rate. Where did you make out the shots came from?’

‘So did I, somewhere about the bottom of the path. Stand by! It’s Algy—here he comes.’ Biggles’s voice rose to a yell as Algy’s familiar figure came into sight at the place where the defile debouched on to the narrow bridge. Crouching low, he sped across the dreadful causeway at a speed that brought the watchers’ hearts into their mouths. He seemed to be trying to re-load as he ran, and that he was successful in this was clear, for suddenly he stopped and sent three shots down the path behind him. But of the enemy at whom he was firing the watchers on the summit could see nothing.

‘They’re after him, and I believe they’re invisible,’ said Biggles, suddenly understanding. Then, raising his voice, ‘Keep going, Algy,’ he roared, and dashing forward a dozen paces, dropped flat with the Lewis gun in front of him. Taking careful aim, he waited until the flying figure rounded a bend which took him out of the line of fire, and then raked the path behind him. Taka-taka-taka-taka-taka . . . taka, taka-taka-taka spat the gun, to the accompaniment of ricocheting bullets. Pieces of rock flew from the ridge and jerked from the rocky walls, but whether or not the enemy suffered it was impossible to tell.

Algy, gasping for breath, appeared at the exit of the half-tunnel and raced towards them, although he was obviously nearing the end of his endurance. He reached the junction of the path and the ledge and then stopped dead. For a moment he swayed, fighting an invisible force; twice he made a stupendous effort to lift the rifle, but the muzzle sagged, and finally the weapon fell from his hands.

The significance of all this was not lost on Biggles. ‘There’s somebody on that ledge,’ he snarled, and sweeping up the Lewis gun, raced down to where Algy was writhing on the ground. He covered the two hundred yards in record time, and was quite prepared for the sight that met his gaze. Lying on the ledge, just round the corner of the rock, was a Chung. His face, reptilian in its cold ferocity, was half hidden behind a black tubular object that was pushed out in front of him, pointing in the direction of the path. He had apparently heard Biggles coming, and was trying to move the tube, but before he could do so Biggles was on him, and with the full force of his fury kicked it out of his hands. Spinning, it disappeared from sight into the chasm, and Biggles, his nostrils quivering with rage, stood over the operator. At that moment the Chung was very near to death, and he appeared to realize it, for he shrank down and shielded his face with his arm. ‘One move, you skunk, and I’ll fill you as full of holes as a sieve,’ growled Biggles, tapping his gun.

The Chung may not have understood the words, but he understood the action and did not attempt to move.

Biggles looked up and saw Algy staggering to his feet. ‘Are you all right, laddie?’ he shouted.

‘Not so bad,’ smiled Algy weakly. ‘I didn’t see that blighter lying there behind that rock; he must have seen me coming, I suppose, and lay in wait for me.’

‘Let’s get back to the top,’ said Biggles, crisply, sending a burst of fire down the path, although he could still see no one. He glanced down at the Chung, and a look of inspiration came into his eyes as he noticed that he was remarkably well dressed, for he wore a robe of purple silk, while a great ruby glittered on his right hand. He was quite young, not more than twenty years of age. Biggles beckoned to Ginger. ‘Give me a hand,’ he said. ‘I’ve a notion to take this young man with us; he may be useful as a hostage.’ He motioned to the man to get up, and the Chung obeyed, although he swayed on his feet and pointed to his right leg. Biggles looked down and saw an ugly red stain.

‘I must have winged this bird last night,’ he said. ‘Never mind, we’ll carry him if necessary. Get hold of his feet, Ginger. Algy, you take the Lewis and watch the path.’

Swiftly, with many anxious glances behind them, they went back up to the summit, but not until Biggles had gathered all the loose rocks that he could find into a sort of rough parapet, and examined the wounded Chung’s injury, which he found was not serious, did he turn to Algy with a curt, ‘Well, and what happened?’ at the same time nodding towards the plateau.

Algy passed his hands wearily over his face. ‘I’ll tell you what I saw, and that’s all I know,’ he began. ‘I may as well tell you right away that when I saw the Chungs on the plateau I had as big a shock as you must have had when you looked down this morning. You left me in charge, so I’m making no excuse; whoever was at fault I accept responsibility. Maybe we were careless; may be the Chungs were too cunning for us; I don’t know. But let me tell you about it from the beginning.

‘I didn’t say much to you before you went because I knew you’d made up your mind to go, but I’d no delusions about the size of the task you’d taken on. I was worried, and it’s no use denying it. As I taxied round and round I was picturing you getting beaten back and arriving at the foot of the cliff with no one there to pull you up. Malty was keeping guard on the hole in the rock door, so he couldn’t do much, but during a lull in the operations I shouted to Dickpa and Mac to drive a stake into the edge of the cliff, tie the rope to it, and leave it coiled ready to drop down to you if you came back. I also told them to keep a look-out for you. All this, you understand, was simply in case you didn’t succeed and tried to get back to the plateau, which was not an unlikely thing to happen, as you must admit.

‘Then we heard the shots, and Ginger fired the signal which told me that you’d cleared the Chungs off the ledge; the rays had gone out, and as everything seemed to be O.K. I stopped the machine, went to Dickpa and Mac, who were still lying on the edge of the cliff as I had told them, and suggested that they might snatch a rest. After all, they are not as young as we are. Off they went to the machine, and I lay down looking into the gorge to see if there were any signs of life. I suppose I was there about ten minutes or a quarter of an hour when a noise made me look up. Don’t ask me how it happened, because I can’t tell you, but I fancy that either the Chungs got busy inside the cave, any noise they made being drowned by the row of my engines, or else they managed to get a ray through the hole and turn it on to Malty. Maybe he dropped off to sleep. I haven’t seen him so I don’t know.

‘As I was saying, I looked round, and there was a bunch of Chungs right up to the machine. There must have been fifty of them. I couldn’t see Malty anywhere; I haven’t seen him since, if it comes to that. Dickpa and Mac were surrounded by Chungs, who were marching them in the direction of the cave. It looked rather as if the Chungs don’t know how many there are in our party, or else they imagined I’d gone on the sortie with you. There I lay unseen, but what could I do? I might have shot a few of them, but what good would that have done? They’d have got me in the end, and there would have been no one to fly the machine up to you. You were hopelessly cut off. So I decided to lie still and wait for a chance to grab the machine if they left it alone. But they didn’t. They didn’t touch it, but just stood around and stared at it as if it was a new kind of animal—which one can well understand.

‘Well, time went on and there I lay. I had no cover, and they couldn’t see me in the dark, but as soon as it started to get light the game was up. One Chung spotted me and that was enough. They came at me with a rush. To get to the machine was out of the question, so I kicked the coil of rope over the cliff, slung the rifle over my shoulder, and started shinning down like a caterpillar. I didn’t waste any time, either. Look at this,’ He held out his hands for inspection, and Biggles caught his breath when he saw how the palms had been lacerated.

‘The Chungs cut the rope when I was about ten feet from the bottom,’ continued Algy. ‘I hit the floor with a bump, and was pretty nearly buried under the rope, but I got free and started off up the gorge like a lamplighter. All the same, I didn’t expect to reach the path. The Chungs on top heaved bricks at me as I went, but luckily they didn’t hit me. I spurted past the centipede cave, and after that I was out of range. The fellows in the cave either saw or heard me go past the entrance, and shot out after me, but I gave them a taste of lead and that quenched their ardour. The sound of the shot brought a bunch tumbling out of the entrance to the path, where they had evidently been concentrating for an attack on you. Goodness! you never saw such a sight. They must have been in the act of doing the invisible man trick. Some had only just started, but some had half gone. They looked like a lot of jelly-fish with human eyes.

‘Well, I didn’t wait to exchange compliments. I gave them four rounds rapid and at that range the bullets went through them like lard. They cleared a lane and I went at them like a bull at a gate. Up the path I went. What a shocking bridge that is! I didn’t see it until I was right on top of it, but when I looked down—well, if you could see my heart, I’ll bet it’s still got teeth marks on it. How I got to the far side I don’t know. I could see the Chungs coming on after me, so up that tunnel place I went like a fox going to earth. Then—but you know the rest. I thought I’d managed to pull it off until at the last minute that yellow-faced dacoit stabbed me with a ray—one of the pocket sort that Mac spoke about, I suppose. The last thing I saw was you charging down the hill, and that was that. So here we are,’ he concluded lamely.

‘Yes,’ nodded Biggles, ‘here we are. What’s happened to Dickpa and Malty, do you suppose?’

‘I see.’ Biggles rubbed his chin. ‘It’s a bit difficult to know what to do, isn’t it?’ he reflected. ‘We could—great suffering rattlesnakes! What’s all this coming?’ he gasped. ‘Looks like a flag of truce. Keep your heads down everybody, it may be a trick. Algy, watch the prisoner.’ With these crisp instructions he crept up to the parapet and stared down the path to where a strange procession had walked slowly into view. First of all came a Chung in a blue and yellow uniform, carrying a white banner. Behind him, pacing slowly beneath a canopy upheld by two attendants, was a commanding figure, resplendent in purple robes. With him, still clad in his shabby overalls, was McAllister, while behind followed a retinue of twenty or more Chungs, also in blue and yellow.

Biggles watched the approach of this impressive parade with interest. ‘Keep your ears open, Ginger,’ he said tersely. ‘There might be an advance guard that we can’t see. But we can hear. If you see a rock move, or hear a pebble rattle, shoot, and we’ll ask questions afterwards.’

But his fears were groundless, and when the cavalcade emerged from the entrance of the tunnel-like portion of the path, which was about two hundred yards below, he stood up and made a peremptory signal for it to halt.

‘You’ll do, Mac,’ he shouted. ‘Tell the boy under the brolly that anything he has to say can be said from there. The first man who puts a foot past that next rock will meet a small piece of nickle-coated lead coming the other way. Got that?’

They watched him speak to the man under the canopy, and then step forward until he was beside the man with the white banner.

‘They’re using me as an interpreter,’ he began. ‘His Highness, Ho Ling Feng, has asked me to say that his son, the Prince Sing Hi, was on the hill when you attacked it last night. He has not returned, so he must have been killed. Ho Ling Feng wishes to recover his body.’

Biggles started, and threw a quick glance at the others. ‘Does this Sing Song fellow wear a purple surplice and a ruby ring?’ he shouted.

‘Centipedes nothing!’ shouted Biggles. ‘Give my compliments to the boss and tell him that Sing Hi is here with us, but if there is any more talk about centipedes, we’ll make him Sing Low—and then pitch him over the cliff.’

‘Don’t do that,’ yelled McAllister in a mild panic, turning to speak to Ho Ling Feng. Presently he turned again. ‘Is the noble Sing Hi hurt?’ he called.

‘He’s got a bullet in the thigh that probably hurts a bit,’ Biggles told him.

‘He’s likely to die at any moment, which may be a serious matter for him, but doesn’t worry us,’ replied Biggles.

‘Just a minute.’ Again McAllister spoke to Ho Ling Feng, and then, turning once more to the summit, ‘He says you’ve got to bring him down at once,’ he called.

‘Nothing doing,’ retorted Biggles curtly. ‘Now you tell the old boy my terms, and if he wants to see his precious offspring again, he’d better fall in line. I’m not going to argue. If he doesn’t agree, he can start padding the hoof back to the royal shack.’

‘Easy nothing. Tell him that I demand the immediate unconditional release of you, Dickpa, and Malty. Malty will come straight up here, bringing his medicine chest, to attend to the casualty. You and Dickpa will go to the machine, under safe conduct, where Algy will meet you and fly you both up to the lake. When the machine lands on the lake with you all on board, two Chungs can come up here with a stretcher and collect young Sing Song—or whatever his name is. And you can tell the head lad that if he makes one false move he will hear a loud pop, which will be his blue-eyed boy hitting the floor of the gorge. Is that clear?’

‘Ay, hold hard.’ McAllister turned to the head of the procession and another conversation took place. Then he faced back up the path. ‘A’richt,’ he shouted. ‘You’ve pulled it off. The old man’s in a fever about the boy, and he’ll do what you say. He’s sending a messenger back to the palace right away.’

‘That’s the spirit,’ cried Biggles. ‘Take your party back to the gorge and stand fast until the machine is here.’

With considerable satisfaction he watched the procession wind its way back down the path until it disappeared from sight in the defile. ‘It looks as if they mean it,’ he told the others. ‘Algy, off you go.’

‘Have you got the brass face to suggest that I walk down that path into the gory clutches of that band of thugs?’

‘Of course. You heard what I said. How else can we get the machine up here? I’d go myself, but it’s up to me to watch the proceedings.’

Algy rose reluctantly to his feet. ‘I’m not exactly dithering with enthusiasm about it,’ he said gloomily. ‘However, I see there’s nothing for it. What do I do?’

‘Just walk back to the plateau, take your seat, wait for Dickpa, Malty, and Mac to get in, and then fly up here.’

Algy eyed the peaks that stood round the lake with misgiving. ‘I suppose I shall be able to get between those,’ he muttered.

‘Try hard,’ suggested Biggles sarcastically. ‘You’ve only got to hit one to settle any question of further mental strain for all of us,’ he concluded grimly.

Algy grinned, and leaving the rifle behind, stepped over the parapet ‘Cheerio—see you presently,’ he nodded, and set off down the path.

Biggles looked at the prisoner, who was lying on the ground staring sullenly at the lake, and then at Ginger. ‘All we can do now is wait,’ he observed. ‘I’ll keep an eye on the path if you’ll watch this streak of purple misery.’

In less than half an hour they saw Malty, accompanied by a small escort of Chungs, walk briskly across the plateau from the direction of the cave. He went into the amphibian, reappeared a moment later with his medicine case, and then hurried back towards the cave.

‘They’ve got a hole through that door apparently; that’s how the blighters got up,’ observed Biggles, who, with one eye still on the path, was watching the proceedings. ‘Upon my Sam,’ he continued, as Algy appeared on the plateau and stopped to have a word with Malty as they met, ‘if this isn’t the craziest business I ever saw in my life.’

Malty disappeared into the cave, to reappear a few minutes later on the narrow bridge at the foot of the path. With him were two stalwart Chungs who carried what appeared to be a bamboo bed. A moment or two later Dickpa and McAllister walked across the plateau to the Explorer and climbed in. Its engine opened up with a roar, and the big machine taxied round to get into the best position for a take-off.

‘Hello, Malty, come and do your stuff,’ greeted Biggles as he stood up and handed over his charge for medical attention, while he watched the Explorer leave the ground, climb up to the lake, make a fair landing, and taxi towards them.

By the time the minor operation had been performed on the wounded Chung, Algy had nosed the amphibian up to the rocks a few yards from where Biggles was waiting, and switched off the engines.

‘Not so bad,’ replied Malty, wiping his hands on a piece of lint. ‘He’ll be all right in a week or two if they keep the wound clean. I’ve finished with him, anyway.’

Biggles turned to McAllister, who had also disembarked, and jabbed his thumb towards the two porters. ‘Tell ’em they can take young Burlington Bertie back to his daddy,’ he grinned.

McAllister complied, and in a few seconds the Chungs were on their way down the path.

‘Don’t ask fool questions; you keep your eye on that path and tell me if you see any ray-throwers or anything moving about,’ Biggles told him.

‘O.K.; but I thought you might have some plan you were waiting to launch,’ answered Ginger, in a hurt voice.

Biggles sat down on a rock and surveyed the party quizzically. ‘Well,’ he said, ‘here we are, and that’s about all there is to say as far as I can see. If any one has a brain-wave, now is the time to air it.’

‘That’s what I was wondering myself,’ replied Biggles moodily. ‘It looks as if we’re in just the same position as we were when we arrived. First we were on the plain. Then we were on the plateau. Now we’re up here. We can’t get any higher, so the next move, if any, will be downwards.’

‘Pretty good,’ sneered Algy. ‘That must have taken a bit of working out.’

‘Come, come,’ put in Dickpa quickly, ‘I’m afraid we’re all a bit upset, and after what has happened it can’t be wondered at; but it’s no good sitting here and bickering.’

‘That’s true enough,’ admitted Biggles. ‘But this affair is getting a bit beyond me, and it’s no use pretending it isn’t. I’m a pilot, not a conjurer. If I remember rightly, the idea of this expedition was to get a packet of radium to save the lives of half a million people who are on beds of sickness—that’s right, Malty, isn’t it? I mean, that’s why you financed the show.’

‘So far, so good,’ continued Biggles. ‘When we get here, we find that the benighted heathens who own the stuff not only refuse to part with any, but try to do us in. What is more, according to Mac, they propose to do the whole world in. Well, it doesn’t seem to be much good trying to save the lives of those sick people if they’re all going to be struck paralytic with this perishing ray in a week or two. Am I right?’

‘Thank you,’ bowed Biggles. ‘Very well; so if we’re going to do anything at all, it is obvious that we must lay low these swipes who are going to upset the civilized apple-cart. Having done that, we return home, having spent a lot of money, and wasted a lot of time, all for nothing.’

‘But what recompense do we get? Who’s going to believe it? No! I defy anybody to disprove that if and when we reach home, we shall be precisely the same as when we started, except that Malty’s bank balance will have had a nasty crack.’

‘The ideal thing seems to be to smite these swipes, and take home a load of radium as well,’ suggested Ginger. ‘What’s wrong with that?’

‘Nothing. Nothing at all,’ replied Biggles. ‘In fact it looks to me as if you’ve hit the original nail on its benign head. Good for you, kid. That’s it; we do both. Strike the swipes and collar the works.’

‘Maybe,’ admitted Biggles. ‘I’ve said it, but saying isn’t enough. How are we going to do it, that’s what I want to know? Both propositions seem to present a certain amount of difficulty.’

‘Well, let’s get some radium for a start. While we’re doing that we can think of a way to choke off the Chungs,’ suggested Algy, who was gazing across the rocky panorama in the direction of the Mountain of Light.

Biggles jumped up and stared at the mile or so of forbidding landscape that separated them from their objective. It consisted of a series of razor-edged ridges, divided by screes of loose shale and masses of fallen rock, that formed a sort of connecting link between the mountain on which they stood and a point about three parts of the way up the Mountain of Light. ‘I wonder if it could be done,’ he said thoughtfully. ‘It wouldn’t exactly be a pleasure hike. D’you happen to know if it’s possible to reach the mountain from here, Mac?’ he asked.

‘I don’t know; I’ve never tried, and I’ve never heard of any one else trying.’

‘Nay, ye wouldn’t do that. No one is allowed to set foot on the mountain.’

‘From the inside. They’ve tunnelled right into the heart of it. It’s friable stuff on the outside, not half so good as the core.’

‘Then we might try it,’ declared Biggles. ‘If we succeeded, then we should at least have accomplished something. But before we go, I’d like to have a look round to get our general bearings. Can we see the town from anywhere up here?’

‘You can, from the dam.’ McAllister pointed to a level step of rock about a quarter of a mile away towards which a vague path wound a sinuous course by the edge of the lake, which was not a lake in the ordinary sense of the word in that there was no suggestion of a beach. The water was held between banks of rock that shelved in some places, and rose sheer in others. In fact, it looked just what it was, a great volume of melted snow-water, pent up by artificial means.

Biggles looked at the path, and then at the dam. ‘I’d like to have a look at the place,’ he told McAllister, ‘but we’d better not all go.’

‘He can have it when we come back,’ replied Biggles. ‘I want him to come with me and show me the layout of the place. The rest of you had better remain on guard. In any case, either Algy or myself should always be with the machine, in case of trouble. If there is anything worth looking at from the dam you can take it in turns to go and look. But we’re not out of the wood yet, remember. Come on, Mac, let’s go and have a look at the old home town.’

They set off along the rocky pathway, picking their way with care, for there were many places where a fall would have meant a broken limb, if nothing worse. Twenty minutes’ hard going brought them to the nearest point of the dam, and as he reached it, Biggles stepped back hastily. ‘My gosh!’ he cried, as he found himself gazing down a sheer drop of some three to four hundred feet. ‘This is certainly no place to play blind man’s buff.’ He pointed to the sheer face of the dam, which was built of great blocks of stone fitted together without mortar or cement. ‘Who was responsible for that not inconsiderable feat of engineering?’ he asked. ‘If we’d built it we should call it one of the wonders of the world,’ he added.

‘Nobody knows,’ replied McAllister. ‘The thing dates back to pre-Chung days, although the Chungs have added to it. It used not to be so high as this, but once or twice after a quick thaw the reservoir overflowed, so the Chungs had to raise it. I believe that has happened two or three times; the Chungs were always a bit nervous about it.’

‘Which I can well believe,’ said Biggles slowly. ‘It would be what you might call a wet night for anybody who happened to be down below if the water got out of hand—eh?’

McAllister nodded. ‘Yes,’ he agreed. ‘Noah’s flood would be a puddle compared with it.’

‘That’s what I was thinking,’ observed Biggles reflectively, lying down to get a nearer view of the face of the dam. It dropped into a dank, sunless gorge which, a few hundred yards farther on, opened out into a round crater-like depression, not unlike the one in which the entrance to the cave of centipedes was situated, but much larger. On the rising ground on the far side was the town, which, in its erratic conception, reminded him of an illustration he had seen, as a small child, of a city of gnomes in a book of fairy tales. There appeared to be no streets, the houses being dotted about at all angles wherever space could be found for them, in typical Oriental fashion. In fact, the only difference between this and the other small eastern towns he had seen was in the material of which the houses were built. As McAllister had said, everything was constructed of a dull brownish-yellow glass-like substance on which, at certain angles, the sun glinted brightly. One or two people, clad in the regulation blue overalls, could be seen moving about.

McAllister raised a finger and pointed. ‘That circular thing over there, like a small gasometer, is the varnish tank,’ he said.

‘You can’t quite see it from here. You notice how the base of the Mountain of Light comes down there on the left, right into the crater?’

‘Well, the entrance is just round the corner there. It is, as I believe I’ve told you, actually in the mountain; and considering that is where the power is drawn from, it is the most natural place for it to be.’

‘Oh, nothing very much,’ replied Biggles casually. ‘Well, there doesn’t seem to be anything much to look at; let’s be getting back.’

Hardly a word was spoken during the return journey. Biggles was deep in thought, and McAllister, after a glance or two at him, decided that it would be better not to interrupt.

‘Does anybody know the time?’ asked Biggles, as they rejoined the others. ‘My watch seems to have gone crazy since we came here.’

‘So have the others, I’ll bet,’ smiled McAllister. ‘You’re too near the mountain. Your watch has become magnetized; you’ll be able to get it demagnetized when you get home, but it’ll never be much more use.’

‘So that’s another item we’ve got to chalk up against the mountain, is it?’ growled Biggles, glancing at the sun. ‘No matter; it isn’t important. I should say it’s about half-past one. What about this trip to get some radium?’

‘Very well. Then the sooner somebody has a shot at it, the better—before the Chungs have another crack at us. They’re not likely to just sit quietly at home and let us wander about as we like. I think Ginger and I had better go.’

‘Sorry, laddie, but I think it would be a tactical error. Suppose anything happened to us? I’m not suggesting that it will—but it might. How are the others going to get home? Ginger might be able to fly them back, but with all due respect to his ability, to expect him, with only a few hours solo logged, to take a big machine like the Explorer all the way to England, would be unfair both to him and his passengers. No, if you don’t mind, Ginger and I will go alone. I suggest taking Ginger because he is nimble, and the trip is going to be a tricky one if I know anything about it. We’ll take a kit-bag with us to put the stuff in—if we get any. Has anybody any other suggestion to make?’

‘That’s that, then,’ he continued, as there was no reply to his question. ‘Ginger, get a kit-bag out of the machine, and the two revolvers. We shall have to leave the guns here, in case the Chungs try anything. Keep your eyes skinned, Algy. I don’t trust them a yard. If it wasn’t for this invisibility trick, we could hold the pass indefinitely; as it is, anything might happen.’ He looked at the mountain, and the route they would have to take to reach it. ‘We shall be gone between two and three hours, as near as one can tell, but don’t get upset if we’re longer,’ he concluded. With a wave of his hand, he started off along the rocky causeway, with Ginger following close behind.

For the first few hundred yards the going was easy, and they made good progress, but as the ridges became steeper they were compelled to exercise more caution. Once they were confronted by what at first appeared to be an unscalable gulch, but by hard and rather heady work they succeeded in reaching the opposite side.

‘I didn’t think it was as bad as this,’ confessed Biggles, as he lay panting on a wind-worn slope after a straight climb of forty feet along the edge of a crevasse. ‘We ought to have brought the rope,’ he declared.

‘Yes, that’s true,’ nodded Biggles, rising and gazing across a terrifying scree that sloped down at an angle of forty-five degrees for a thousand feet or more. ‘It looks as if one loose stone here might start a landslide of considerable dimensions,’ he observed anxiously. ‘Take it easy, and test every rock before you trust your weight on it.’

They went on again, feeling their way slowly and leaning well in towards the face of the slope. As careful as they were, small pieces of rock broke off from time to time and went bounding and crashing down into the depths, but after ten minutes of nerve-trying labour, during which time neither of them spoke, they reached easier country again.

‘That’s the worst of limestone,’ muttered Biggles, looking back over the path they had just traversed. ‘It looks safe but it’s as rotten as tinder. Treacherous stuff.’

‘By jove, so it is,’ answered Biggles. ‘It isn’t more than a quarter of a mile away, either, and looks fairly easy to reach from here. I wish I’d known it. We could have taxied across, landed over there, and saved ourselves a lot of trouble. We shall know in future. Come on, let’s keep going. My gosh! look at that, though!’ He had taken a pace forward, but stopped dead as a new hazard, made apparent by the different angle from which they were now approaching, loomed up.

Their objective was now within easy reach, connected to the rock on which they were standing by a bow-shaped, serrated ridge; but on the left, between the mountain and the lake, was a colossal spur. At one time it had obviously been part of the mountain, but erosion or an earth tremor had torn it away from its parent, so that it became a separate mass of rock, balanced on a wholly inadequate foundation and leaning far over towards the lake. From the aeroplane, the dividing cleft had been hidden behind the spur so that the mountain appeared to be one solid mass, but from their new view-point, the real state of affairs was disclosed.

‘My goodness! did you ever see anything like that?’ whispered Ginger. ‘It looks as if a shove would send the whole thing crashing over.’

Biggles eyed the mighty mass of rock apprehensively. ‘It looks as if it would fall if you breathed on it,’ he muttered. ‘By heaven, did you see that? It actually sways in the breeze. I swear I saw it move.’

Ginger turned pale, and regarded the pile fearfully. ‘And we’ve got to pass it, too,’ he whispered.

‘We have—if we’re going to the mountain,’ declared Biggles. ‘I don’t think we need worry, though. It may have been standing like that for years for all we know, and may go on standing for more years. It will come down one day, of course, but it would be a bit of bad luck if it chose the very moment that we were passing, wouldn’t it?’

‘You’re right—it would—for us,’ agreed Ginger fervently. ‘With a hundred thousand tons of rock on us, we should take a bit of finding.’

‘It won’t fall this way in any case,’ said Biggles thoughtfully. ‘It will go the way it is leaning, which is towards the lake. And it would about half fill it, too. Still, if you’re nervous, you stay here,’ he suggested.

Without another glance at the towering rock they went forward again, crossed the saddle-backed ridge, where a false step would have hurled them to certain death, and at the end of ten minutes stood on the broad flank of the Mountain of Light.

‘Where do we start collecting radium?’ asked Ginger. ‘This rock all looks alike to me.’

‘And to me,’ admitted Biggles. ‘We want to make sure of getting the right stuff. We should look fools if we carted a load of ordinary rock home, shouldn’t we? Let’s go on a bit. Look out—mind that hole.’ He pointed to a round hole about the size of a small table-top that lay in Ginger’s path.

They passed on, examining the rock as they went, and saw several more holes. Biggles stopped near one of them. ‘What are these things?’ he said curiously. ‘They look as if they might be the burrows of some whacking great animal.’ Casually, he picked up a piece of rock and tossed it in. For two or three seconds there was silence, and then they heard it clatter far down in the heart of the mountain. As it struck they looked at each other, both a trifle pale.

‘I don’t know,’ replied Biggles slowly, ‘but it looks to me as if they might be sort of ventilation holes—blow-holes; something to do with the power-station underneath, perhaps. Hark, can you hear anything—a sort of distant hum?’

‘Yes, I can hear it distinctly,’ cried Ginger. ‘It sounds like an engine running.’

‘That’s what I thought,’ returned Biggles. ‘I don’t think much of this. The sooner we get back to the lake the happier I shall be. Let’s get some of this radium stuff and go. That’s it over there, isn’t it? I can see it glowing, even in daylight.’ He pointed to a face of rock a few yards away. ‘Stand fast, I’ll get some,’ he cried, and started towards it; but at the second step he stopped dead and stared at the ground. ‘Ginger,’ he said, in a strained voice, ‘this place sounds hollow to me. I believe we’re standing on nothing more than a thin crust. You can hear it ring—hark!’ He raised his foot and brought his heel sharply on the ground. There was a hollow booming sound, quickly followed by a loud snap, and then, like thin ice on which a heavy weight has been dropped, the whole surface of the rock caved in.

He made a desperate effort to save himself. As he felt the ground giving under his feet, he flung himself sideways, and did actually succeed in clutching the edge of the fracture. For a second he clung to it with his fingers, trying to haul himself over the lip, but the whole piece broke away in his hands, and he plunged downwards into utter darkness.

Ginger, ashen faced, watched the earth literally open and swallow him up, but it took some seconds for the full horror of the calamity to penetrate into his stunned brain, so sudden had it been. Trembling like a leaf, he lay flat and wormed his way to the very edge of the hole, and saw at once, with a sharp intake of breath, what had happened. As Biggles had said, they had been walking on a crust, a thin shell of rock not more than two inches in thickness. Somewhere in the depths rocks were still rolling. ‘Biggles!’ he shouted hoarsely. There was no reply. ‘Biggles!’ he yelled again, desperately, but there was no answering hail. Slowly the rocks stopped falling, and all was silent.

How long he lay and stared into the black mouth of the hole he could not afterwards remember, but it must have been some time, for when at last he wriggled away to solid ground and rose to his feet the sun was sinking behind the mountains.

Suddenly making up his mind, he turned his back on the scene of the tragedy and set off at a steady run towards the lake.

When Biggles felt the rock break away in his hands he gave himself up for lost, but as often happens in such cases, a hundred thoughts flashed through his racing brain. Paramount was anger with himself for the folly of the action that, in a moment of thoughtlessness, had resulted in the accident. As he fell, he instinctively covered his face with his arms and braced himself for the coming shock.

It came sooner than he expected. The distance he fell sheer was not, he judged, much more than twenty feet, but he landed on a steeply sloping plane, and before he could steady himself he was rolling over and over with a mass of detritus farther down towards the heart of the mountain, grabbing wildly about him for anything that would check his wild progress. Several times his hands came into contact with solid rock, but in spite of his utter disregard for torn finger-nails, he could find no projection sufficient to arrest his fall. His last sensation before losing consciousness was that he was being stoned to death. Something struck him a violent blow on the head; a constellation of brilliant orange stars, fading slowly to crimson, soared before his eyes, and he knew no more.

His first conscious thought, as he came round, was a dreadful conviction that he was blind. He could not recall what had happened, but he knew that he had opened his eyes; yet he could not see. Everything was as black as the tomb. He tried to get up, but a great weight was pressing on his chest. For a moment he struggled, and then, in a flash, he remembered. Stiffly he pushed aside the debris that was half smothering him, sat upright, and felt in his pocket for matches.

In the Stygian darkness the first one he struck almost blinded him, but as his eyes grew accustomed to the light, it revealed his position clearly. He was lying in a steeply sloping tunnel-shaped cave about five feet high. From the dog’s-leg bend in which he lay, and which apparently had broken his fall, he could see it stretching away upwards and beyond him.

Painfully he got to his feet and examined himself, and it was with heartfelt relief that he discovered that no bones were broken. He was badly bruised, as was only to be expected, and his finger-tips were torn and bleeding. There was a nasty patch of damp hair just above his forehead, where his head must have come in contact with the rock at the bend, but it did not seem to be a very serious matter. He struck another match, shook the worst of the rubbish from his clothes, and was just preparing to try to work his way back up the slope when the silence was broken by a vibrant hum that started on a low note, climbed a little, and then remained constant. He knew what it was. Somewhere not far away a powerful electric motor had been started.

For some moments he stood still, listening, staring down into the darkness of the passage from which the sound was coming. Was it imagination, or was there a faint luminous glow at the far end? There seemed to be—something. ‘This path I’m on must lead to the works,’ he mused. ‘Whether it is natural or artificial, there is no doubt of that. Maybe I’m in some old workings. If they lead into the big power-station . . . I might as well have a look, anyway, so that I shall know what I’ve got to face if I can’t get back to the top of the shaft.’

Slowly, feeling his way by the wall, he set off down the cave. Once a streak of blue light appeared at his side, and he started, only to smile a moment later as he realized that the cause was part of the same phenomenon that illuminated the peak outside. He saw the same thing several times as he went on, and presently found that the distant gleam of light that had first attracted his attention was but another, although a much brighter, example of it.

The noise of the motor was now much louder, and it became increasingly evident that it was not far away, so he determined that, having come so far, he would see the matter through. He had been descending a steep gradient all the time, but the incline now became almost precipitous, so he sat down and allowed himself to slide forward on an imaginary toboggan, regulating his progress by pressure on the floor.

Somewhat to his surprise, the cave suddenly widened out, and finally emerged into one of those cathedral-like chambers that are a common feature in limestone caves. Enormous stalactites and stalagmites hung from the ceiling and rose up from the floor, but these were not the common form. They were faintly luminous, and shed an unearthly radiance over the whole cavern, giving Biggles the impression that he had entered one of those fearsome infernos of legend and fable. That the place was of natural and not artificial formation was apparent at once; no human being could have imagined, much less carved, the intricate lace-like tracery that covered the walls and ceiling.

He broke the top off one of the smaller stalagmites, broke it again, examined the pieces closely, and then dropped them into his pocket. ‘Queer stuff,’ he mused. ‘I suppose it must be radium, although I thought radium was only found in pitch-blende. Is it—oh, I don’t know,’ he concluded impatiently; and taking care to mark down the position of the tunnel from which he had emerged, he hurried across the spectral chamber in the direction of the noise that now filled the air.

Twice he walked completely round the cave looking for a continuation of the tunnel, and was about to abandon the quest, thinking that he had been mistaken in his assumption that there was one, when a noise brought his heart into his mouth. It was the unmistakable sound of a hammer striking on rock not far away, and it came from a twisted skein of stalagmites in the far corner.

Revolver in hand, he made his way slowly towards the place, and feeling his way through a labyrinth of glowing columns, found himself gazing upon a scene so strange, so utterly out of place, that although he had been half prepared, he was lost in the wonder of it. About forty feet below, and covering an area of more than an acre, was the most incredible power-station he had ever seen. An engine of the dynamo type was running, and into a bell-shaped receptacle above it a number of naked Chungs were throwing small pieces of what seemed to be white-hot metal, which they were hammering out of a pile of rock that lay beside them. This was being brought to the spot by other Chungs who were working in a gallery almost at his own level. Beyond the dynamo, and separated from it by a high metal grille, were rows of what appeared to be enormous accumulators, or storage batteries; made of yellow glass, they were so large that they dwarfed a man who was standing beside them.

For some time Biggles stood and watched the amazing scene, and then, remembering the anxiety the others must be feeling on his account, he turned away. As he did so, he trod on a loose stone. It turned under his foot and, to save himself from falling, he clutched wildly at a long fluted stalagmite that rose up like an ivory column towards the ceiling. It snapped like a carrot and came down with a crash, breaking several others in its fall, and he went down under a pile of debris. Aghast at the noise he had made, he scrambled to his feet and threw a swift look at the workers to see if he had been heard. One glance was enough. The Chungs had stopped work and, in various attitudes of surprise, were staring at the spot. As his head came into view there was a shrill yelp of alarm, and a general rush was made in his direction.

He had dropped his revolver in the fall, and now sought it with frantic haste, but apparently it had been buried under the fragments of rock, for there was no sign of it. The Chungs were now almost on him, so he could tarry no longer, and cursing himself for his stupidity, he was compelled to abandon it and made a dash at the labyrinth. In his haste he took the wrong turning; it ended in a cul-de-sac, and by the time he had discovered his mistake, the leading Chung, a burly fellow, was within a yard of him with hammer raised ready to strike.

Biggles felt the old fighting lust surge through him and his lips came together in a hard line. With a deft movement he snapped the top of a stalagmite, and using both hands, brought it crashing down on the man’s head. The three-foot length of radium-impregnated limestone burst like a rocket into a shower of pale blue sparks, and the Chung went down like a log. Still clutching the short thick length of the improvised weapon that remained in his hand, he leapt over his fallen adversary and dashed down the right corridor, just as the main body of Chungs swept into the far end of the labyrinth from the gallery.

A wild yell went up as he came into view, but he heeded it not and raced for the big chamber. Reaching it, he turned and hurled the weapon with all his force into the long tapering stalactites that hung like rows of organ-pipes from the roof. It whirled through the air like a torch and crashed into the target with a noise of splintering glass. Several of the stalactites snapped off, and falling on to the Chungs, tripped them up. They in turn, as Biggles had done a few moments earlier, clutched at the stalagmites to save themselves from falling, but they were as brittle as icicles, and crashing down, only added to the confusion.

Biggles hesitated only long enough to seize another length of limestone to use as a weapon, and then made a rush for the cave in the far corner. He reached it before the Chungs had recovered, and without waiting to see if they were following, darted into it like a rabbit going into a burrow. To his surprise and joy, he discovered that a faint light emanated from the length of rock he was carrying, so holding it before him like a lantern, he was able to make good progress.

For ten minutes or more he hurried on, and then stopped to listen. Somewhere far away he could hear various noises; the strange chattering voices of his pursuers, and the sound of scurrying footsteps. They seemed to be all around him so he went on, frowning as a fresh doubt came into his mind. In the confusion of thought following his return to consciousness, he had assumed that Ginger had escaped the fate that had befallen him, and had remained safely on the mountain side, in which case he would be certain to return to the Explorer for assistance. But it now struck him with an unpleasant thrill of apprehension that the lad might have fallen into the mountain as well; he might even be lying smothered under the debris at the head of the tunnel.

Panting from exertion and dripping with perspiration, he hurried on, blaming himself for not thinking of it before. ‘I should have gone straight back,’ he told himself savagely, and then jerked to a standstill as a yellow light flared up ahead. It disappeared again, but he stood still, listening intently and staring into the blackness, waiting for it to reappear. A faint noise reached his ears, and then he understood. Some one was coming down the cave, striking matches as he came, but a moment’s reflection told him that it was unlikely that the Chungs could have got beyond him, so it could only be one of his own party.

‘Hello, there,’ he shouted, and then flinched as the noise of his voice boomed up and down the low corridor.

The approaching footsteps stopped abruptly, so he hurried on towards them. ‘All right, it’s me,’ he said quietly, realizing that the light-bearer would be startled.

‘By gosh! you were just in time,’ came Algy’s voice. ‘I was just going to shoot. I thought it was a brontosaurus, or something, in search of its prey. I’m nothing for this subterranean stuff. Thank God you’re alive, old lad. We thought you were a goner.’

‘So did I,’ answered Biggles, grimly, as they met. ‘But don’t let’s stop and talk now. The Chungs are on the trail.’

‘Where have you been all this time?’ asked Algy, as they set off up the passage.

‘I got knocked out when I fell, and when I came round I stopped to have a look at the power-station.’

‘Yes, it’s just below. I’ll tell you all about it later on. How did you get here?’

‘Ginger came back to the boat as white as a sheet and told us that you’d fallen into a hole in the middle of the mountain. We taxied the machine across to this side of the lake—Ginger showed us where we could land—and formed a rescue party. When we got to the hole we discovered it wasn’t so deep after all, and I half expected to find you unconscious at the bottom. We had brought the anchor rope from the machine, so the others let me down to look for you. When I couldn’t find you at the bottom, I knew you must be down here somewhere, so I was going to keep on until I found you.’

‘We had to. Our one concern was to get you out. It took all hands to lower me, anyway. And if you’d been seriously hurt it would have taken the lot of us to carry you back to the boat.’

‘I don’t know, but I don’t remember this level stretch. I swear I didn’t come down it. Did you notice any side turnings when you came down?’

‘Yes, there were two or three higher up, down the part where you must have slid, and one later on, a sort of Y fork.’

‘Then we’ve taken the wrong turning,’ declared Biggles. ‘Let’s go back. We must watch for an opening on the right now; don’t let’s go past it.’

‘Here we are; this must be it,’ said Biggles, with a sigh of relief, as a dark hole showed in the wall on their right. ‘Thank goodness! I’d hate to be lost in here. I don’t hear the Chungs any longer, but they’re bound to be hunting for me, so we shall have to watch our steps.’

A few minutes later the cave suddenly opened cut into a chamber so vast that the ceiling could not be seen, even with the help of a lighted match. Biggles’s jaw set grimly. ‘What’s this?’ he snapped. ‘We’re wrong again.’

Biggles swung round on his heel, struck another match, and found himself staring at half a dozen door-like openings set close together in the wall. ‘Which of those caves did we just come out of?’ he asked in a strange voice.

‘All right; let’s keep going; it’s no use sitting down and crying about it. We must try to find a path that leads uphill. Let’s go across to the far side of this place and see if there is a continuation of the passage we came up.’

‘No,’ he continued some minutes later, after they had made a complete survey of the vast apartment. ‘There’s no way out this side. It’s a dead end. Let’s go back; I don’t suppose we shall strike the passage we came up, but we might as well go somewhere.’

Half an hour later, in a narrow corridor, he stopped again. ‘Got a cigarette on you?’ he asked. ‘Thanks. I’m afraid this looks like a bad business,’ he murmured.

‘We don’t seem to be able to strike a path that goes straight uphill, although I think we’re higher than we were; the place is a regular honeycomb. If we can’t go up we shall have to go down; maybe we’ll find the power-station. I’d rather try to beat my way out through the Chungs than wander about in this catacomb much longer.’

They set off again, no longer with any fixed purpose other than to find a way out of the mountain, anywhere. They had long ago abandoned the idea of striking the original path, or even of recognizing it if they did.

Biggles, who was leading, suddenly threw himself backwards with a gasp. For a moment or two he was so shaken that he could hardly speak. ‘Look!’ he said in a low voice. ‘I forgot it was dark outside; I nearly stepped over.’

Algy craned forward and peered over his shoulder. A great black wall confronted him; far above it a single star twinkled in the sky. ‘What is it?’ he asked in a hushed whisper.

‘None. The path just ends in the face of the rock. If we were flies we could crawl up, but we’re not. If we had a four hundred foot rope we might get down—but I doubt it. We haven’t, so it’s no use talking about it. Still, it’s something to have seen the sky and to know it’s still there. Come on, let’s go back.’

Returning, they found a narrow opening which seemed to lead upwards. They followed it for a few yards and then came to a blank end. Above them rose a chimney-like hole, like the shaft of a mine. At the top, a hundred feet above them, was a small circular patch of star-studded sky.

Biggles laughed bitterly. ‘Tough luck again,’ he said. ‘We can’t get up there. Back we go.’

Again they retraced their footsteps, and for a little while plodded on in silence. They found a path that led steeply upwards; it was little more than a crack in the rock but they went up it with renewed hope. The walls began to glow with a weird phosphorescent light.

‘It looks to me as if we’re getting near the summit,’ remarked Biggles. ‘What queer stuff this is,’ he went on, pointing at a particularly bright patch on the wall. He raised the length of stalagmite he was still carrying, and struck it a sharp blow. There was a cloud of tiny blue sparks and then he staggered back as the whole wall fell outwards and the cave was flooded with a dazzling blue radiance. The cave had become a narrow cornice on the side of the mountain. Neither spoke. Below them lay the lake, shining like a floodlit sea, while all around towered the mountains, reflecting the pale light of the one on which they stood.

‘There’s Dickpa and the others; I can see them still sitting by the hole,’ cried Algy.

But Biggles was not listening. Instinctively his eyes had sought the place where the Explorer should have been moored. He clutched Algy’s arm. ‘It’s gone,’ he cried hoarsely.

Algy stared, and swallowed something in his throat. ‘Yes,’ he echoed in a hollow voice. ‘It’s gone—no, there she is, over there.’ He raised his arm and pointed.

Biggles, following the line, saw the amphibian floating far out on the broad bosom of the lake.

Biggles shielded his eyes with his hands. ‘Is it my imagination, or is the right wing low?’ he said, in a tense voice. ‘If I didn’t know that such a thing was impossible, I should say she was sinking. Look how deep she is in the water. Why, the lower port wing is almost touching.’

‘Let’s hail the others; they’re not more than a quarter of a mile away.’

‘Better not; the Chungs may hear us. Steady how you go, and don’t trust the rock more than you must; it’s as rotten as tinder on the outside.’

Half-way down the steep slope a large piece of rock broke away and crashed downward, carrying a shower of smaller pieces with it. At the sound of the landslide, three figures, crouching near the edge of the hole, started up.

‘It’s all right, it’s us,’ called Biggles, seeing that they were uncertain how to act.

Five minutes later they met, and Biggles cut short the Professor’s congratulations on his escape. ‘What’s happened to the machine?’ he asked curtly.

‘Happened to it? Nothing, as far as I know. We thought we’d better keep a guard on it, so Ginger went back about half an hour ago.’

‘We left the machine moored against the rock, just this side of the dam, where we disembarked.’

‘Well, it isn’t there now. It’s out on the lake, and I don’t like the look of it. The sooner we get along and see what’s wrong, the better.’

For some time the Explorer was hidden from sight owing to the saucer-like depression through which they were compelled to pass, but when they finally ran up on to the far lip, which was only a short distance from the edge of the lake, Biggles pulled up with a cry of consternation.

The reason was instantly apparent to the others. There was no doubt about it: the Explorer was sinking. Her hull was low in the water, and her wing-floats were half submerged.

‘Nothing,’ replied Biggles. ‘Absolutely nothing. I doubt if there is a log of wood, much less a boat, within hundreds of miles of us, and to swim out to her is out of the question. That water is as cold as ice; I’ve tested it, so I know. A swimmer couldn’t live in it for a minute. If you have any doubt about it, just try.’

‘Are we going to stand here and watch her sink without making an effort to save her?’ cried the Professor.

‘Apparently,’ replied Biggles harshly. ‘We can’t work miracles. Where’s Ginger, though? That’s what I’m wondering.’

‘He must be on board,’ replied Algy. ‘How else could the machine have got there?’

‘She’s drifted. If the mooring rope was cut or untied, the breeze would carry her out.’

They all sat down and for some time watched the Explorer sinking deeper into the water. Their hearts sank with her. Then Biggles got up and began pacing up and down. ‘How far is she from the far side, do you think, Algy?’ he said. ‘I mean, will she drift right across before she sinks, because if so, we might work our way round to her.’

‘I should say she is as far from the other side as she is from this,’ answered Algy moodily. ‘She’s just about in the middle.’

‘Then nothing can be done,’ declared Biggles. ‘If Ginger is aboard her, then he’s lost, but I don’t think he can be, or he’d shout or fire a signal, or do something. Why doesn’t he start the engines?’

As if in answer, one of the Explorer’s engines came to life with a roar, and a moment later, after two misfires, the other followed.

‘Thank God,’ cried Biggles fervently. ‘The young blighter must have been asleep, and has just woke up. Still, that doesn’t explain why she’s so low in the water. Here he comes. I’ll give him something when he gets here for putting us to all this suspense.’

Standing in a line on the bank, they watched the amphibian plough its way slowly through the placid water towards them, and when the bow ground gently against the rock Biggles was wearing an expression that boded no good to the pilot. Before he could speak, however, the cockpit cover was thrown back; Ginger’s head appeared, and all thoughts of admonition were at once forgotten. His face was ghastly and smeared with blood.

But Ginger cut him short. ‘Quick,’ he croaked, ‘start bailing her out. She’s got a bad leak. I’ve stuffed the hole up as well as I can, but the water’s still coming in.’

Biggles waited to hear no more. He sprang into the cockpit and dived through the low doorway that gave access to the cabin. The first thing he saw in the dim light was the naked body of a Chung, half submerged in the water with which the cabin was flooded. With scant ceremony he heaved it overboard, where it sank in the deep water. ‘Get buckets—cans—anything,’ he said tersely to Algy, who had followed him. ‘Here, hand this gun out to the others and tell them to keep sharp watch. Malty can attend to Ginger; the poor kid looks as if he needs attention.’

They set to work feverishly to bale out the water, and presently were joined by Ginger, who, in spite of their protests, insisted that he was well enough to help.

Biggles made no further demur, for the matter of emptying the boat was pressing, and when at last the leak came into view as the machine rose slowly in the water, he looked at it curiously. It was a perfectly round hole the size of a tea-cup, and had been hastily stuffed up with a wad of rag.

‘How did that happen?’ he said shortly, speaking for the first time since Ginger had joined them.

‘That Chung did it—or rather, the ray he brought with him,’ replied Ginger, without stopping work. ‘I caught him in the cabin and we had a rough house. I won, but I went down for the count at the end. The ray must have been working, because when I came round it was lying there, hissing like an acetylene blow-lamp, and had punched a hole clean through the hull. I stuffed it up, and seeing you all standing here, taxied back.’

‘You were just about in time, too,’ grunted Biggles, as he continued scooping out the ice-cold water with a canvas bucket. ‘Another five minutes, and you’d have sunk.’

Ginger nodded, with an eye on the hole. ‘Lucky it wasn’t any lower,’ he observed. ‘I think we can patch that up all right.’

‘I’ll rivet a piece of metal over it; there’s some duralumin in the spare-part locker. You keep on bailing.’

He succeeded in putting a fairly neat patch over the leak, which, when caulked round the outside, kept the water out, but it took a long time, and dawn was breaking when at last he picked up his tools with a satisfied exclamation.

Tired, wet, cold, and hungry, they went ashore and stamped up and down to restore some life into their numbed limbs.

‘Get the stove going, and brew a gallon or two of hot coffee, Malty,’ ordered Biggles. ‘Mind it’s scalding hot. And fry some bacon. I’d hate to catch my death of cold.’

Over a quickly prepared but satisfying meal Ginger told his story. He was still pale, and it was clear that he had been more shaken than he would have the others believe.

‘When I left you to come back to the machine,’ he began, looking at the Professor, ‘I had an uncomfortable feeling about leaving the pass unguarded, but I wasn’t really expecting trouble—not for a bit, anyway. As you know, it was dark except for the light of the mountain, but I could see the machine riding comfortably just as we had left her, so everything seemed to be all right in that direction. I went on board and started getting the primus stove ready, with the object of knocking up a bit of supper against your return.

‘While I was in the cabin something happened that set me thinking. The machine had swung round a bit so that her wing was quite close to the bank, and I thought at first that she had bumped, for there was a sudden jerk that made her tilt over. I went to the porthole and looked out, but she was riding clear, which struck me as a bit odd, but I came to the conclusion that she had bumped herself away from the rock. I know now that it was a Chung getting on board by stepping on to the wing; it’s plain enough to see afterwards. But one is apt to overlook this invisible stunt, and when I looked out and saw nothing, I thought no more about it—which shows how careful we’ve got to be.

‘Actually there were two Chungs at least; there may have been more, but I only know of two. I was filling the kettle out of the water-bottle when the boat tilted again, so much so that I spilt some of the water. There seemed to be no reason for it, although it felt just as if somebody had jumped on board. I went to the window again and looked a bit more carefully, and noticed that the port wing was low, as if there was a weight on it. Then in a flash I guessed what was up, and I was right. If a Chung had come on board, I knew he must be still standing there on the wing, by the way it sagged. There seemed to be only one thing to do. I opened the porthole a little way, and still standing inside out of sight, I fired my revolver, aiming between the two outside inter-plane struts. The first time nothing happened, so I fired again, this time behind the rear strut. That got him. There was a terrific splash as if a sack of bricks had fallen into the water, and the wing jerked up to normal. I couldn’t see anything, remember. You may have heard the shots.’

‘I did hear something, now you mention it,’ declared Dickpa, ‘but the sound was muffled and sounded so far away that I didn’t attach much importance to it, worried sick as I was about Biggles.’

‘It was because I was inside the cabin that the shots were muffled,’ resumed Ginger. ‘Well, the fellow falling into the water put the wind up me properly, as if there was one there were likely to be more, and I’d no means of telling how many there were, so I went to dash out to yell for help. As I bolted through the hatch I barged into somebody coming in, a fellow who had evidently come aboard by the nose. That must have been the second bump I felt. I couldn’t see him, mind you; it’s a ghastly sensation, feeling somebody you can’t see.

‘Anyway, I fell backwards inside, and the other fellow fell in too, judging by the noise. I saw a black tube roll across the floor, and knowing what it was, and if the guy once got it going it was all up, I made a jump to get it first. I had dropped my gun when I fell, but I didn’t bother about that. My one idea was to heave the ray gadget overboard. As I ducked to get it, it sprang into the air, apparently of its own accord, and fetched me a bang over the head. Down I went, and by a bit of luck fell on the revolver. I could hardly see for blood, but I whipped it up and let drive. Something heavy came crashing down on top of me, and that’s all I knew about it.

‘When I came round I was lying in a fairly deep puddle of water, and for a bit I couldn’t make out what the dickens had happened. Was it cold? I should say it was. Maybe it was the cold that brought me round. The first thing I saw was the dead Chung lying beside me, and the next, the water pouring through the hole where the ray, which was still active, was playing on the side of the hull. I soon had it overboard and ran up on deck to shout for help. I nearly fainted again when I saw where I was. However, I ran back into the cabin and plugged the hole as well as I could. Then I started the engines and made for the shore. I saw you standing here, and when I saw Biggles was with you I didn’t care much what happened. And here I am: that’s all,’ concluded Ginger dispassionately.

‘And what’s the position now?’ asked Algy. ‘If we’re going to do anything, it’d better be soon,’ he added.

Biggles nodded. ‘You’re right,’ he said; ‘we can’t hang about here much longer.’

‘Did you get any radium?’ asked Malty, remembering the object of the assault on the mountain.

Biggles handed him a long pale-grey piece of stalagmite that he had brought back. ‘Is that any use?’ he asked. ‘If so, I’ve some more pieces in my pocket.’

‘Doesn’t seem to be an awful lot to come all this way for, does it?’ put in Ginger ruefully. ‘It looks like a fossilized walking-stick to me.’

‘Well, we can only hope for the best,’ said Malty when he had finished. ‘I’ll put it aboard.’

‘And what now?’ asked Algy. ‘Is it worth while going back to the pass and trying to hold it?’

‘I don’t think so,’ replied Biggles slowly. ‘For all we know, there may be Chungs up there already. Even now they may be setting up a ray battery somewhere close at hand. Personally, I’m in favour of leaving them to it.’

‘Going home. What are we staying here for, anyway? We’ve got a little of what we came here for, haven’t we? Is it enough to have made the trip worth while, Malty? If it isn’t, I’ll go back to the mountain for more, but delay is dangerous, and obviously I’d rather not. You put up the cash, so it’s up to you to decide.’

‘I agree with you,’ replied Malty, without hesitation. ‘There’s no sense in losing our lives trying to be greedy. Radium or no radium, I’m all for getting back. I’ve got a specimen of the stuff, and that suits me. There’s no doubt that we took on a bigger job than we bargained for when we came here. If we’d known before we came what we——’

‘Yes, quite,’ cut in Biggles, ‘but let’s stick to facts. It’s no use talking about what might have been—that won’t get us anywhere. The only thing that worries me is what Mac has told us. If what he says is true, then it’s up to us to try to put a spoke in the Chungs’ wheel before we go back and report the matter to the Government, or the League of Nations, or whoever will have to deal with it—not that they’ll be likely to believe us.’

Biggles glanced at the sky, across which low, dark clouds were scurrying. ‘I don’t like the look of those,’ he said shortly. There’s weather brewing, or I’m a Dutchman.’ He turned to McAllister. ‘Mac,’ he said earnestly, ‘I suppose there is absolutely no doubt whatever in your mind that these people really are a menace to civilization? You think there is a chance that they may accomplish what they are out to do?’

‘More than a chance,’ declared McAllister. ‘I’ve lived with them for years, so I ought to know. If they don’t wipe out civilization, they’ll kill thousands of people in China and India trying, and so upset things that it will take half a century to recover. They’ll mop up India for a start, if nothing else. They’re used to mountain altitudes, and the Himalayas will no more stop them than a two-foot fence would stop a hunted stag.’

‘Very well, then we’ll take your word for it.’ Biggles turned to the others. ‘I’ve a plan, and one only,’ he said. ‘I’ll tell you what it is. Afterwards, if any one can think of anything better, let’s hear it. We can’t take the place by storm: that’s out of the question. The best we can hope for is to put the power-station out of action. That would set them back for a time, anyway. That’s so, Mac, isn’t it?’

‘Then we must bust the power-station if we can, and the only way we can do that as far as I can see is to flood it.’

‘By causing the lake to overflow. That hole I fell through is a hundred feet lower than the lake. The bank here, which is the nearest point to it, is also lower than anywhere else. If the water rises, it will pour over here first. It will flood the depression behind us, and pour down the hole like the waste-pipe of a sink.’

‘It would,’ agreed Dickpa, ‘if the water overflowed. How are you going to make it do that? I thought you were going to suggest bursting the dam.’

‘That would be the ideal thing, if we had any way of doing it, but nothing short of a heavy charge of dynamite would shift those rocks,’ replied Biggles. ‘I had a thundering good look at them the first time I went there, with that object in view, but I came to the conclusion that it couldn’t be done.’

‘So we will, if my plan fails, but don’t forget that people will be wondering what has happened to us by this time, and when we turn up some awkward questions may be asked. We may find it more difficult to get out of India next time.’

Biggles pointed to the great spur of rock that overhung the lake. ‘A squib would bring that lot down,’ he declared. ‘And when it falls it’s bound to go into the lake. It will displace thousands of tons of water, and the water has to go somewhere. It’ll go the only way it can—over the bank here and into the depression.’

‘That lot going over would be a sight worth seeing, wouldn’t it?’ smiled Ginger at last.

‘There’s only one way,’ answered Biggles. ‘If we break down all the ammunition we’ve got we can produce a fair pile of cordite. We’ll tamp it into the base, and fire it off.’

‘We’ll use petrol. We can lay a train of petrol all the way from the rock to here as we come back. We’ll light it, take off, and hope for the best. We can get everything all ready before we go, engines running, and so on. There won’t be any time to lose.’

‘You’re right, there won’t,’ observed Dickpa dryly. ‘And once we take off, we go straight back home, I suppose?’

‘That’s the idea. We couldn’t land on the lake again, anyway, and with no ammunition and precious little petrol, we should be fools to try landing anywhere this side of India.’

‘Very well, then, let’s set about it. Get the tools out, Ginger, and let’s start breaking down the cartridges. Everything goes in—revolver ammunition—Very lights—anything that will help to swell the bang.’

It took them two hours, working at feverish speed, to complete the job. Biggles and Algy ripped the bullets out with pliers; Dickpa and Malty emptied the cases, and Ginger pressed the yellow cord-like substance, from which the explosive takes its name, into biscuit tins. All camp equipment and everything not required for the journey home was then unloaded and thrown on the bank.

As he worked Biggles kept one eye on the now lowering sky. ‘It looks as if we shall just about be in time,’ he said once, quietly, to Algy.

When all was ready, he siphoned out of the main tank into sundry containers as much petrol as he thought would be needed to lay the train, and then he called the others together.

‘These are the orders,’ he said, ‘and I need hardly say that everything hangs on this thing panning out according to plan. It has got to be timed perfectly. If we aren’t off the water by the time the rocks fall—well——’ He made an expressive gesture. ‘Algy, you’ll sit in your usual place in the cockpit, with engines running and everything ready for a snappy take-off. Leave my place ready for me to jump into. We’ll start the engines before I leave to make sure there’s no delay there. Ginger, you’ll come with me and help me to carry the stuff. Malty, you’ll remain ashore with the Lewis gun and keep an eye open for Chungs. I’ve left twenty-five rounds in the gun in case of accidents, so if you do have to shoot, use your ammunition sparingly. When you see me coming back within a hundred yards of the machine, abandon the gun and get aboard. We don’t want to lumber ourselves up with unnecessary equipment at this stage. You, Dickpa, and Mac will take your seats in the machine and stay there. Is that all clear? Good! Then we’ll start. Algy, go and get the engines going.’ He glanced up at the sky, now heavy with dark, threatening clouds, but whatever he thought of them, he said nothing. He waited for the engines to start, and then, picking up the tins of cordite, and indicating the petrol supply to Ginger, he set off quickly towards the objective.

Neither he nor Ginger spoke a word during the journey; the task was plain and there was no need to comment. As they reached the formidable mass of rock which they hoped to precipitate into the lake, a flash of lightning forked downwards from the clouds to one of the distant peaks, and a moment later a sullen clap of thunder boomed and echoed through the rocky fastnesses about them.

‘I’m not deaf,’ snapped Biggles, for after the events of the last few days his temper was inclined to be a trifle short.

‘The rock’s swaying in the wind,’ muttered Ginger, paling as he glanced upwards.

‘I’m sorry, but I can’t stop it if it is,’ grunted Biggles, as he eyed the mass wonderingly, for not until he actually stood beside it did he realize just what an amazing freak of nature it was, although he recalled that the same thing occurred in a lesser degree in different parts of the world, even in Great Britain. Erosion by wind, and water pouring down the mountain during the spring thaw for countless centuries, had worn away the base of the rock, which at the top was a hundred yards or more across, until it was balanced on little more than a feeble stalk that had cracked in several places under the colossal pressure from above. So frail was the foot in comparison with the huge bulk it carried that, as Ginger had said, it moved slightly as each gust of wind struck it.

‘We’ve got to put the charge in on this side, to make quite certain it falls the right way,’ muttered Biggles.

‘How about this?’ Ginger pointed to a wide crack that gaped open at the very foot. As the mass moved with the wind, the crack opened even wider, and closed again as it moved back ponderously to its original position.

‘The very place,’ declared Biggles. ‘If we stuff the cordite in when the crack is wide open, the hole will automatically tamp itself as the rock comes back into place. Help me to open these tins.’

Working swiftly, they thrust the explosive into the crack, forcing it home with a piece of sharp stone. Another vivid flash of lightning blazed through the air not far away, and a vicious roll of thunder made the whole mountain tremble. They completed the task with a burst of feverish energy.

‘That ought to do the trick, I think,’ mused Biggles, standing back to survey their handiwork. ‘Now for the petrol.’ He started as another flash of lightning forked downwards almost simultaneously with its accompaniment of thunder. ‘My goodness, did you see that?’ he muttered, in a startled voice. ‘Let’s get a move on. It would be a fluke if the lightning hit the rock just as this moment, but I shall feel happier when I’m a bit farther away from it.’ Picking up a tin of petrol, he splashed some of the spirit over the cordite, and then began to run back towards the lake, allowing the petrol to trickle out as he went.

They were still two hundreds yards away from where Malty was standing on guard when another flash of lightning darted down into the mountain, so close to them that they were both thrown off their feet.

Biggles was up first, looking slightly dazed. ‘Quick—the last lap,’ he gasped.

Ginger sprang up, and in the act of passing the final can, happened to glance behind along the way they had come. He turned as white as a sheet. ‘Look! he screamed, ‘the petrol’s alight!’

Biggles took one look and saw that he was right; the lightning had fired the fuse. He dropped the can with a crash. ‘Run for it!’ he yelled.

Like mountain goats gone mad they tore towards the boat, leaping from rock to rock regardless of risk, regardless of anything in their frenzied haste to get aboard the Explorer before the charge exploded. As they ran they shouted desperate warnings to the others.

‘In you go, Ginger, and shut the door,’ yelled Biggles, as he took a flying leap into his seat. Without waiting to strap himself in, he moved the throttle wide open, and as the big machine moved forward, swung her round in her own length to get head to wind. Out of the corner of his eye he could see a yellow flame speeding across the rocks; it was within twenty yards of the spur.

Under the impulse of her powerful engines, the Explorer surged forward, leaving a trail of creamy foam in her wake, but she had not reached anything like the speed necessary to lift her from the water when there was a flash, quickly followed by a sharp, ringing explosion.

None of those who saw what followed will ever forget the sight. Their hearts seemed to stop beating. The great spur quivered, hung for a moment, and then, slowly and majestically, swept through the air. It struck the water with a roar like thunder, and was instantly lost to sight in a cloud of spray that rose into the air almost as high as the Mountain of Light. A second later, out of the white mist, a great wall of water emerged and bore down on the amphibian with the speed of an express train.

Biggles knew it would come and had already started to turn before it appeared. His face was grey and his lips were set, for in his heart he thought they were lost. If the wall of water caught them it would be the end; that was certain. An ocean liner would have been thrown on its beam ends and swept from stem to stern by such a wave. The lightly-built flying boat would just crumple up like so much tissue paper. He did not look at Algy. He got the machine round until it was facing in the opposite direction, and saw at once that there was not enough room to get off except at one point. The dam.

Nowhere had he a run of more than a quarter of a mile, which was barely enough to enable the Explorer to get off even if the shore had been flat. But it was not. At all points except at the dam steep banks of rock rose high into the air.

To attempt to clear them was out of the question. At the dam, however, they broke away into a narrow cleft, leaving only the low wall of the dam to clear. Was the gap wide enough to permit the Explorer to pass through? He did not know. He did not think so, but it was the only chance left. Vaguely he recalled stories he had heard of pilots flying under the Forth Bridge, and between the centre columns of the Arc de Triomphe, in Paris. Not once since he started had he touched the throttle, and now, with engines roaring, he set his nose at the dam. A swift glance over his shoulder showed the mighty wall not more than thirty yards behind, towering high into the air. He could never have visualized anything like it. It far out-stripped his wildest imagination.

A hundred yards from the dam the wave had half closed the distance between them, and was beginning to curl over at the top as if hungry to engulf the flimsy scrap of metal and fabric with its human freight. With joystick well forward, he set his eyes on the centre of the dam and watched it apparently rushing towards him. Within ten seconds their fate would be settled. He could see now that the boat could get through—if she would leave the water. Would she unstick? He eased the stick back gently and the feel of it told him all he needed to know. She had not gathered enough speed to rise in the rarefied atmosphere. Fifty yards—forty—thirty—twenty—he seized the stick firmly, intending to drag her off even at the risk of a stall. Death was staring him in the face; the manner of it was immaterial. He knew now that a crash was inevitable, and braced himself for the shock.

What happened next occurred in a nightmare-like horror of sight and sound. Magically, almost at the moment of impact, the dam disappeared, and he clutched his instrument board with his left hand as his seat seemed to drop out from under him. The sensation was as if the machine had struck an enormous bump. Through whirling wraiths of white mist he saw the walls of the gulch on either side of him, and, with the amazing perception of detail that often comes at moments of great mental strain, he actually noticed the burrow-like hole in the wall through which he and Algy had peered out not many hours before. Below, a great bow of green water curved through the air and plunged into an incredible cauldron of foam with a roar like the end of the world. Then everything was swallowed up in a curtain of blinding mist.

Yet not for a moment did he lose his head. He still held the joystick firmly although it had gone slack in his grasp, but as he felt it grow taut again he eased it back, and his nostrils quivered as he felt the machine answer to the control. It shot out of the mist, and the town of the Chungs swam into view below. Whatever was happening behind them, they were saved.

He swept up exultantly over their old landing-ground on the plateau, and then and not before did he allow himself to relax. Indeed, he could not help it, so great had been the strain of the last few seconds. He glanced at Algy, chalk white and sitting bolt upright in his seat, caught his eye and smiled. He knew, that if it were possible, the experience had been even worse for him, for being a passenger he had been unable to do anything but watch and wait for the end.

Algy shook his head sadly and passed his hand wearily over his eyes. Then he leaned over. ‘Let’s go home,’ he shouted above the noise of the engine. ‘I can’t stand this sort of thing.’

‘Go and see how the others are getting on,’ shouted Biggles in reply, as he started banking in a wide circle back towards the scene of the maelstrom, to try to see just what had happened.

As his wing swung clear, exposing the view beyond, his lips parted in an expression of utter astonishment. The lake had disappeared. Where it had been yawned a huge crater, grey with the deposit of ages. A second glance revealed the reason. The dam was no longer there, although the spot was clearly marked by a wide breach in the rocks at the head of the gulch. Had he not known that it could not be so, he would have thought that the tidal wave had washed the dam clean away, but he knew that was not the case, for the dam had burst before the wave had struck it. He could only conclude, therefore, that the dam had collapsed under the pressure of some terrific under-water pulsation.

In the absence of the spur, the riven side of the Mountain of Light stood out stark like a cut cheese. He took all these things in at once, and then his lips went dry as his eyes sought the water and found it. It was pouring from the gulch into the crater on the side of which the town was situated, in a two hundred feet high wall of swirling foam that toppled over as the pressure on its flanks was released, and spread itself out in a sea of tossing brown waves and coiling whirlpools. The flood had not yet reached the town itself, but it was perilously near, and the inhabitants were pouring up the hill in order to escape the deluge. At the far end of the crater the water was running like a mill-race down-hill along the gorge of the centipedes. Already it had almost filled the lower crater near the plateau, and was tearing down the continuation of the gorge towards the plain.

At the opposite end of the turmoil it had reached the foot of the Mountain of Light. Biggles could not see the entrance to the power-station, so he concluded that it had already been submerged. He felt a nudge at his elbow, and turning, saw Algy beside him.

Biggles nodded towards the flood. ‘We succeeded better than we expected,’ he muttered. ‘Did you ever see anything like that in your life? Have a good look, for I doubt if you’ll ever see anything like it again.’

Algy opened his mouth to reply, but no words came. He could only point. All around the upper part of the mountain clouds of steam were gushing from what Biggles had once called blow-holes. It was easy to guess what had happened. Either an explosion had taken place in the power-station or the flooded storage batteries were generating gas that was being forced upwards by the pressure of the water below. This supposition was supported by the fact that the jets of steam increased in volume and intensity as the water in the crater increased in depth. But even so, the small holes could not emit the gas fast enough, and the thin sides of the mountain began to collapse in several places. Landslides poured down into the water, and these, by causing the water to rise higher, only made matters worse.

‘Well, I don’t think they’ll start any world-conquest for a bit,’ continued Biggles, as he swung low over their old camping-ground, and applied left rudder to bring the machine on what he knew from the landmarks to be the homeward course. Automatically, his eyes went to the compass. The needle seemed to be strangely steady. It did not even vibrate in its customary manner. ‘What’s the matter with the thing?’ he thought, as he deliberately banked slightly to see what the result would be. The needle did not move.

His heart gave a lurch when he realized that the instrument was out of order, and what the consequences were likely to be. He glanced at the sky and then at the ground. The thunderstorm still persisted, with vivid flashes of lightning darting into the ground on all sides, but this did not worry him. It was the fact of the sky being completely covered by sombre, solid-looking cloud that caused the corners of his mouth to turn down and a frown to furrow his forehead. He nudged Algy on the arm and put a finger on the glass of the compass.

Algy looked, leaned forward for a closer view, and understanding what had happened, opened his eyes wide. ‘What are you going to do?’ he shouted.

‘I shall have to go down,’ answered Biggles shortly; and cutting the throttle, he began losing height, with his eyes searching the ground for a likely landing-place.

It was not necessary to look far, for before them and on all sides stretched the rolling plain. There appeared to be no rocks or other obstructions, but in the circumstances, and knowing what a dire calamity a faulty landing would mean, he was by no means happy. He lowered the wheels, but for nearly five minutes he circled low over the place he had chosen before he would risk landing.

The wheels touched softly, and he breathed more freely as the Explorer slowed down and finally ran to a standstill, although not until he was on the ground did he realize how hard the wind was blowing. He glanced around, and satisfied that they had no enemies to fear, he went through into the cabin. Algy followed.

‘But if you continued to fly south-west, you’d be bound to strike the Himalayas sooner or later. You couldn’t miss them.’

‘Not if I continued to fly south-west, of course I couldn’t,’ retorted Biggles coldly. ‘What do you think I am, a pigeon? Could you point to the south-west?’

They all trooped out on to the short grass. Malty looked back at the now distant mountains, faced about and pointed.

‘Precisely,’ put in Biggles. ‘Now perhaps you understand. Even with the mountains as a guide no one is sure to within an angle of thirty degrees. What do you suppose it will be like in half an hour, when we are out of sight of the mountains, and only the plain, which all looks alike, underneath us? Add to that the facts that a thirty-mile-an-hour wind is blowing, and we have only just enough petrol left to reach India by flying in a dead straight line, and it should not be hard to see what will happen if we drift off our course. I saw a little of the Himalayas as we came over them, and what I saw makes me confident that they’re easier to fly over than walk over—which is what we should have to do if we were forced to land this side of them through running out of juice. As I have told you before, I’m a pilot, not a chamois.’

The Professor glanced up at the clouds. ‘You could keep a fairly straight course if you could see the sun, I suppose?’

‘On the other hand, it may not. I don’t want to appear unduly pessimistic, but judging from the look of things up topsides, the sun will have to put in some spade-work if it is going to break through that muck today.’

‘We’re already at fourteen thousand feet,’ Biggles reminded him. ‘That is the altitude of the plateau on which we stand. The ceiling is, for a guess, two thousand feet above us. By that I mean the bottom of the clouds. Judging from my experience, I should say that those clouds are five thousand feet thick if they’re an inch. That takes us to over twenty thousand feet, which is a bit beyond us, I’m afraid.’

‘Let’s have a look at the compass,’ broke in Ginger. ‘Perhaps the needle has stuck.’

‘Be careful what you’re doing,’ Biggles warned him. ‘They’re tricky things. I wouldn’t touch it, and that’s a fact. I once took one to pieces, and when I put it together again I had enough bits left over to make two wireless sets and a gramophone.’

Biggles, Ginger, and Algy returned to the cockpit, while the others went into the cabin out of the icy blast.

Ginger tried tapping the side of the instrument, but the needle was as rigid as if it was screwed down. Then, without warning, as they watched, it vibrated violently, and then flashed round in a swift semicircle. Again it quivered, and then began a series of rapid jerks.

Biggles put his hand to his head, eyes agog. ‘Great goodness!’ he gasped. ‘Did you ever see anything like that? The thing must have got a bug in it. This isn’t a compass, it’s a stop-watch. I can’t bear to look at it. Wait a minute! What an ass I am. I’d forgotten about my pocket compass.’ He groped under his coat and took out the instrument, glanced at the dial, shook it and looked again. ‘No use,’ he said briefly. ‘Funny thing, but this one’s stuck, too.’ Then he sprang upright, a look of understanding dawning in his eyes. He darted through the low doorway into the cabin, where the Professor and Malty were examining with interest the pieces of stalagmite he had brought from the cave. ‘What are you doing with that?’ he shouted.

The others jumped. ‘Doing with it? Nothing—just looking at it, that’s all,’ replied Malty.

A slow smile spread over Biggles’s face. ‘I’m afraid you’ll have to throw it away,’ he said reluctantly.

‘Well, I’m not parting with it,’ declared Malty. ‘If necessary, I’ll get out and walk. This is what I came for and I’m not going back without it.’

Biggles scratched his ear. ‘It seems a pity to dump it, I admit,’ he said slowly. ‘But honestly, Malty, I daren’t risk flying without a compass, so what are we going to do about it? That stuff must fairly bristle with magnetism, or electricity, or both—yet why doesn’t it affect the magnetos?’ he added quickly.

‘They’re varnished, that’s why,’ put in McAllister, speaking for the first time.

‘We’ve no varnish,’ McAllister pointed out. ‘We used it all on the plateau and left the bottle behind. Wait! I’ve got it. Malty, take the stuff outside; go some distance away and see if the compass is all right then.’

At a distance of a hundred yards the compass began to show signs of life; at two hundred it was normal.

Biggles breathed a sigh of relief. ‘It looks as if we shall have to dump it,’ he said.

‘Why not roll the stuff up in a piece of sheet and let it hang out of the window—out of range, so to speak.’

Biggles stared and then laughed. ‘Nothing like having a practical man on board,’ he said. ‘Let’s try it.’

A coil of copper wire was produced from the spare-part locker and the cause of the trouble attached to one end of it. Biggles took off, and smiled as the small bundle trailed out below and behind them. He glanced at the compass and then turned to Algy. ‘Tell them it’s O.K.,’ he said, ‘and remind them to wind it in before I land. We don’t want to hook the roof off the rest-house.’

Eight hours later, after an uneventful voyage, the Explorer landed on the aerodrome at Chittagong, just as the sun was going down behind the mysterious jungle.

Biggles looked up in surprise, pretending not to notice half a dozen silver machines bearing the red, white, and blue insignia of the Royal Air Force, lined up in front of the hangar, and a dozen curious spectators in khaki drill uniforms, who were watching from the veranda. ‘We got a bit off course, I’m afraid,’ he confessed.

‘Off your course!’ cried the official incredulously. ‘Are you trying to tell me that you’ve been in the air ever since you left here?’

‘Oh, no,’ replied Biggles naively. ‘We had some engine trouble and came down.’

‘Over there.’ Biggles indicated the north-east horizon with a vague sweep of his arm.

‘I thought you said you’d got a bit off your course,’ observed the official sarcastically.

‘It may have been some way; the compass went wrong,’ Biggles told him casually.

‘I should think it was some way,’ muttered the official pointedly. ‘I happen to know that country. A helicopter couldn’t find room to land this side of the Himalayas, much less that.’ He pointed to the Explorer. ‘I’d like to see that compass,’ he went on grimly.

The official looked at the instrument and grunted. ‘Yes, that’s not much good,’ he admitted. ‘You ought to be more careful with your instruments,’ he advised.

Biggles did not think it worth while to explain that a part of their cargo, now once more in the cabin, was responsible for the rigidity of the needle.

‘Half a dozen service machines have been wasting their time looking for you for the last twenty-four hours,’ went on the official.

‘That’s not my fault, is it?’ protested Biggles. ‘What do you mean, wasting their time, anyway?’

The official looked at him oddly. ‘Because they would have had to go a long way before they found you, wouldn’t they?’ he said meaningly. Then a slow smile spread over his face, and when he spoke again it was in a different voice. ‘I should dearly love to know just what you people have been up to,’ he murmured. ‘Would it surprise you to know that Marshal Li Chen has sent a nasty note to the British Legation in Pekin, requesting that the pilot of the British aeroplane that is annoying certain of his subjects be requested to return to his own country.’

Biggles started. ‘Li Chen! I seem to have heard that name,’ he said, with a puzzled air.

‘I shouldn’t be surprised; he’s the head of the Chinese Government. A very powerful man at the moment.’

‘I remember. Sort of jumped up from the ranks, and now trying to do the Dictator act.’

‘I’m sorry, laddie, but I’m afraid I can’t help you,’ replied Biggles sadly. ‘I was never in China in my life. And now, if this little catechism is over, my party could do with a spot of nourishment.’

‘What are you going to do tomorrow?’ asked the official, as they walked slowly towards the rest-house. ‘I mean, which way are you going? Or are you going to stay here?’

Biggles looked him straight in the eyes. ‘At the crack of dawn we are going back to England, Home and Beauty, just as fast as we can,’ he said softly.

The other smiled. ‘I think that would be the very best thing you could do,’ he agreed. ‘You’re featuring on the front pages of the world’s newspapers at the moment, under the headlines of “Missing British Fliers. Mystery of Lost ’Plane,” so don’t be surprised if the reporters ask you some leading questions.’

A fortnight later they sat in the library at Brendenhall Manor, sipping their after-dinner coffee. They had gone down by train after spending a day in London, during which time Malty had taken the pieces of stalagmite to an unknown destination, and Biggles had reported to the Foreign Office in answer to a curt invitation handed to him on landing. The Explorer had been left at Brooklands Aerodrome to be re-conditioned.

‘So you told them the whole story,’ said the Professor, looking at Biggles, who had just finished describing his interview in London.

‘Of course. It was no use beating about the bush. They had every right to know, anyway.’

‘Nothing. They’re better at listening than talking. When I’d finished they just said “Thank you” and handed me my hat. But if you want my opinion, I should say from a general impression that they were relieved. I had a feeling all the time I was there that they knew more than they pretended; that something funny was going on in the Far East, but they weren’t sure what it was. There’s no doubt that the affair was more far-reaching than we first imagined. This Li Chen johnny has big ideas. The Foreign Office people knew that, of course, but they didn’t know what they were. They do now.’

‘Unquestionably. He was financing them out of the Chinese Treasury and supplying transport for the machinery to the Tibetan frontier; he was all set to step in at the finish and openly proclaim himself Lord of Creation. The Chungs must have got the money from somewhere to buy the plant for harnessing the power supplied by the mountain. Where did they get it? I didn’t notice any goldmines or other prolific sources of revenue about, did you?’

‘And drawn attention to the fact that they had radium deposits? Not likely! That would have been enough to bring the spies of every financial magnate in the world hotfoot to the spot. Then the game would have been up. No! The radium was too big a secret to be let drop. Li Chen backed them with a world-conquest in view, so that if it had come off it would have been a good investment. The joke is, he can’t do anything about it now. If he starts a scream he’ll expose his own plot, and that wouldn’t do him much good. The big Powers would keep such an eye on him in future that he wouldn’t be able to change his socks without their being aware of it. But what I want to know is, what have you done with the loot, Malty?’

‘Yes; that ’phone call I answered a little while ago was from the Royal Institute. I’ve been waiting for you to stop talking so that I could tell you what they said.’

Malty flushed with an excitement he could no longer conceal. ‘The stalagmites contain a high content of a hitherto unknown form of radium,’ he said in a low voice that he strove to keep steady. ‘The question of monetary values does not arise. It is beyond price. It is estimated that when the metal is extracted from the limestone there will be at least three ounces—probably more.’

‘Yes, ounces. Of course, it was impossible to think of radium in such enormous quantities,’ continued Malty breathlessly. ‘A grain is a lot, you know.’

Biggles looked relieved. ‘Then our little lot will be worth quite a bit,’ he suggested.

Malty smiled. ‘My dear fellow,’ he said, ‘if you are thinking in terms of L. s. d., the valuation figure could not be less than two hundred and fifty thousand pounds, although that is purely problematical, because as radium has never existed in such quantities, nobody is qualified to name a price.’

Biggles sank back suddenly. ‘Two—two—my goodness,’ he stammered. ‘I’d have brought back a hundredweight if I’d known that.’

Biggles blinked. ‘What are you going to do with it then?’ he asked. ‘Put it on the mantelpiece for a souvenir, or use it as a paper-weight, or something?’

‘No; after allowing the Radium Institute to take what they require for research purposes, I shall distribute it between the leading hospitals in the country. There will be ample to go round.’ Malty hesitated. ‘I have not lost sight of the fact, however, that you have all been to some trouble in the matter, so I don’t propose to leave you out. Personally, I am more than satisfied with the way things have panned out. For Mac here, without whose kindly assistance we might now be whitened skeletons in the gorge of the centipedes, I have instructed my agent to buy a cottage on the banks of the Clyde.’ He raised his hand to cut short the old man’s rhapsody of thanks, and then turned to Biggles. ‘Would it satisfy you and your two loyal comrades—er—that is—would you consider yourselves recompensed if I handed the Explorer over to you, with sufficient funds to finance another trip to anywhere you care to go?’

‘For my part, Malty, I call that really handsome; nothing would suit me better,’ declared Biggles. He turned to Algy. ‘How about you, laddie?’ he asked.

Misspelled words and printer errors have been corrected. Where multiple spellings occur, majority use has been employed.

CONTENTS


	The S.O.S.
	Dickpa’s Story
	The Roof of the World
	The Mountain of Light
	The Silver Stream
	Marooned
	Angus tells his Story
	An Anxious Night
	A Grim Journey
	Biggles Declares War
	Council of War
	Biggles Disappears
	What Happened to Ginger
	Deluge
	Reflections

THE S.O.S.

DICKPA’S STORY

THE ROOF OF THE WORLD

THE MOUNTAIN OF LIGHT

THE SILVER STREAM

MAROONED

ANGUS TELLS HIS STORY

AN ANXIOUS NIGHT

A GRIM JOURNEY

BIGGLES DECLARES WAR

COUNCIL OF WAR

BIGGLES DISAPPEARS

WHAT HAPPENED TO GINGER

DELUGE

REFLECTIONS