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The Great Airport Mystery

“IT’S ROBBERY, BUT I’LL SELL THE PLANE,” THE HARDY BOYS HEARD OLLIE JACOBS SAY.

Printed in the United States of America

“It’s certainly great to have an airport so close to Barmet Bay,” said Frank Hardy.

“I wish we could go up in an airplane some time,” returned Joe, his brother.

“Wouldn’t you be scared?”

“Me? Would you?”

“No.”

“Then I wouldn’t be scared either. Look at the record holders! Where would they be now if they’d been afraid to go up in an airplane?”

“That’s right,” said Frank. “Airplanes are pretty safe nowadays. Almost as safe as this car of ours.”

The two Hardy brothers were driving on the Shore Road, leading out of Bayport and skirting Barmet Bay, in their new roadster. It was springtime. Snow had disappeared from the hillsides and the blue waters of the bay sparkled in the sunlight. Their destination this afternoon was the new airport, a few miles out of the city.

“I’m glad winter is over, even if we did have a lot of fun on Cabin Island,” said Joe. “It won’t be long now before we’re through school.”

“If we pass our exams,” Frank reminded him, calmly.

“You’ll pass all right. I’m not so sure about myself. I had to work mighty hard to catch up to you.”

“Yes, but I lost a term that year I was sick. Anyway, our marks have been good this year. We should get through. Isn’t it funny—when we’re going to high school we wish we were out of it and now that we are in our last term I’m rather sorry to leave.”

“Me, too,” said Joe. “Wonder where we’ll be next fall?”

“College, I guess.”

“Mother has her mind set on a college course for both of us. So far as I’m concerned I’d rather go into detective work with dad.”

“It would certainly be more exciting. Still, we’d have a good time at college, I imagine,” observed Frank.

He turned the car into a road that branched off the main highway. This road led toward the airport that had been constructed back of Bayport the previous summer.

“Wonder why they built the airport so far out,” Joe said.

“They have to have plenty of ground. It was the only place available. Then, there’s a railway siding near by and a train always meets the mail planes,” Frank explained. “Dad was telling me all about it the other evening. They use the port for commercial flying too, and I hear they do a lot of business and hope to do more.”

“An airmail pilot must have lots of nerve. It’s marvelous that they nearly always bring the mail through on time. And lots faster than trains. I wish we knew one of the pilots. He might take us up for a flight.”

“Chet Morton and the rest of the fellows would be green with envy,” rejoined Frank.

The roadster bounced along the rutted road toward the airport. A signpost near by conveyed the information that the flying field was three miles away. A little later, as the car came over the brow of a hill the Hardy boys could see the great flat field lying in the valley below. In front of a hangar they could see a plane with silver wings.

“Chances are we’ll both have a plane of our own in about ten years,” Joe said. “Everybody will be flying then, and think nothing of it.”

Frank applied the brakes as the roadster descended the steep grade. In a few minutes they had reached the foot of the hill. The car raced along the level road toward the airport.

The boys had often seen the airplanes flying over the city, but they had never been in close proximity to one of the machines and now they were excited over the prospect.

“Perhaps,” said Frank, “we’ll even meet one of the pilots and have a chance to talk to him and hear about some of his adventures.”

Joe turned in his seat and looked back.

“Why, there’s a plane now!” he exclaimed. “We’ll be able to see it land.”

Above the roar of the car the boys could hear the hum of an approaching airplane. It came swooping down out of the sky beyond the hill.

“Seems to be flying mighty queerly,” commented Frank. “Usually they go along as smoothly as a bird.”

“Nothing smooth about that one. Maybe the pilot’s in trouble.”

The flight of the plane was indeed erratic. It was going from side to side in a jerky fashion and it seemed to be flying much closer to the ground than safety warranted.

“He’ll never reach the airport at that rate,” said Frank, looking back again. “He should be higher up than that. Look! He’s coming straight down, and the airport is a couple of miles away!”

“I hope he doesn’t land on the road. He might hit us.”

“If he lands on the road he’s in for a nasty crash. A plane has to have plenty of room to move around in.”

Between steering the roadster and eying the plane, Frank Hardy was well occupied. Joe kept looking back and staring at the descending machine.

“I believe that fellow is in trouble,” he said. “He’s coming down right this way.”

They could see the airplane quite clearly now. They could even see the figure of the pilot in the cockpit. The machine was descending at terrific speed in a long glide that made it seem inevitable that the plane would fall far short of the airport.

Frank stepped on the accelerator. The car leaped forward, raising a cloud of dust. But the speed of the car was as nothing compared with the speed of the plane. The distance between them diminished, and the plane was steadily nearing the ground.

“Great Caesar! That fellow is coming down on top of us!” shouted Joe, in alarm.

“Not if I can help it,” returned Frank grimly.

Joe looked up. He could even distinguish details of the understructure of the airplane now. The roar of its engine was deafening. Lower and lower it came.

For a moment the plane flew level. Its nose raised and it gained altitude. Joe breathed a sigh of relief. Then the big machine dipped again. He could see the propeller blades flashing in the sun.

The roadster was traveling at sixty miles an hour. Frank did not dare raise his eyes from the road. He crouched over the wheel.

“Where is he now?” he snapped.

“Right behind us! And coming down every minute!”

Joe was really frightened. There was no hope that the plane would ever reach the airport, for it was flying too close to the ground. He wondered if the pilot was merely trying to scare them. But the plane was diving toward them in such headlong fashion that he quickly abandoned this explanation.

Powerful though the roadster was, the speed of the plane was much greater. It was scarcely two hundred feet from the ground now and its nose was pointing down at a dangerous angle. In a few more seconds there would be a crash, and, from the angle of flight, it seemed almost certain that the heavy machine would crash directly on top of the roadster!

The car roared ahead, the noise of its engine drowned in the gigantic throbbing of the airplane’s motor. The plane came nearer and nearer, diving at almost incredible speed.

“We’re done for!” groaned Joe.

Unless a miracle intervened the plane would crash directly on top of the Hardy boys’ car!

Frank Hardy could scarcely keep the car on the road. He glanced at the speedometer. They were traveling at seventy miles an hour.

It was certain that the airplane would crash on the highway.

Suddenly Joe leaned forward.

“Look! The side road!” he shouted. “Take the side road!”

A short distance ahead Frank saw a rough dirt road leading off the highway to the airport. If he could only reach it in time! The roar of the descending airplane was deafening now. They could even hear the wind screaming in the struts. Joe saw the pilot, in helmet and goggles, waving his arm wildly.

Frank slackened speed slightly as he neared the dirt road, bore down on the wheel, and made the turn. The rear wheels skidded wildly, there was a screech of brakes, the car teetered perilously, then righted itself, and shot down the rough lane.

At the same moment the airplane roared past. It was so close that the wing tip came within a few feet of the rear of the car.

Then it crashed.

Frank was having his own troubles and he did not see the crack-up. On the bumpy dirt road the car skidded, throwing up a cloud of sand and dust, then shot across a ditch, thumped and lurched over some rocks, and finally came to a stop at a rail fence.

Joe came close to going through the windshield and then hit the door with a thud.

“Wow!” he burst out. “Some wild ride, I’ll tell the universe!”

Frank had been thrown tightly against the wheel, otherwise he, too, might have gone into the glass. As it was, he hurt his ribs a little.

“Well, I’m glad we didn’t overturn,” he remarked, as soon as he could catch his breath.

“Or take down the fence.”

“Wonder who that crazy fellow was?”

“Maybe something went wrong with his air bus.”

“Well, I’m glad we managed to get from under. It was a mighty close call.”

Joe, looking back, saw the airplane as it crashed.

Nose-down, it came, then flattened out just before it reached the ground. Its understructure crashed into the earth. The plane seemed to bound high in the air, then came down again with a snapping and crackling of wood, and buried its nose in the dust of the road. Then its tail canted up and the plane turned a somersault over on its back.

It was a wreck!

While the Hardy boys are scrambling out of their roadster and hastening back to the scene of the airplane crash that had so nearly cost them their own lives, the opportunity will be taken to introduce them more definitely.

Frank and Joe Hardy were the sons of Fenton Hardy, an internationally famous detective, late of the New York police force. Mr. Hardy had made such a name for himself as a detective with the New York force that he had resigned to go into business for himself as a private detective and his services were frequently sought in important cases. His sons, Frank and Joe, were eager to follow in his footsteps.

The Hardys lived in Bayport, a thriving city on Barmet Bay, on the Atlantic coast. Here Frank and Joe attended the Bayport high school, where they were in their final year. Although Frank, a tall, dark, handsome lad, was a year older than his curly-headed brother Joe, both boys were in the same grade because of an illness that had caused Frank to lose time. Mr. and Mrs. Hardy were anxious that their sons should go to college after finishing high school, Mrs. Hardy wishing them to study law and medicine. But the boys were of different mind. Their father’s profession appealed to them. They wanted to be detectives.

As a matter of fact, the lads had a natural bent toward detective work and they had already proved their ability so thoroughly that Fenton Hardy was disposed to believe that they would be successful if they followed in his footsteps. The Hardy boys had solved a number of mysteries that had puzzled the police of Bayport and vicinity, and already the people of the city knew of them as boys possessing more than the usual share of initiative, resourcefulness, and deductive ability.

Frank and Joe were introduced in the first volume of this series, entitled: “The Hardy Boys: The Tower Treasure,” in which they solved the mystery of the disappearance of a treasure from Tower Mansion, on the outskirts of Bayport. In succeeding volumes of the series their adventures while seeking to unravel other mysterious cases in which they became involved have been described at length. During the winter previous to the time this present story opens, Frank and Joe Hardy had spent a vacation on Cabin Island, in Barmet Bay, where they had cleared up the mystery of a stolen stamp collection of great value, discovering the precious stamps after many thrilling events. These adventures have been related in “The Mystery of Cabin Island,” the volume immediately previous to this story.

As the Hardy boys ran back down the dirt road toward the wreckage of the airplane they had little hope that they would find the pilot alive.

“He’ll be smashed to pieces!” gasped Joe.

“The plane isn’t burning, anyway,” said Frank. “There may be a chance for him yet.”

Just then they heard a cry for help.

It came from beneath the jumbled wreckage of the plane. In a few moments the Hardy boys reached the scene.

Although the crash had been witnessed from the airport and people were already proceeding toward the spot, the Hardy boys were the first to arrive. They could hear groans and shouts from beneath the plane.

“We’ll have to lift up some of that wreckage to get the poor fellow out,” said Frank quickly. He looked around. It was futile to attempt raising the wreckage by hand. He saw a heavy rail lying at the base of the near-by fence. “Here we are. This will do as a lever.”

The boys seized the rail and carried it over to the wreckage. They inserted one end of the rail beneath the body of the plane, rolling a big rock forward as a support.

The groans and shouts continued.

“All right there!” called Frank. “We’re going to pry some of this wreckage away from you. Are you badly hurt?”

“I’m nearly killed,” groaned the pilot. “Hurry up and lift this plane off me.”

“Try to crawl out when we raise it,” advised Frank.

The boys bore down on their improvised lever. There was a clattering and crackling of the wreckage; then the mass began to move. The body of the upturned plane rose slightly. Joe caught a glimpse of the pilot scrambling out of the cockpit. The man’s face was scratched and bleeding, but he seemed to be crawling out of his precarious position quickly, so evidently no bones were broken.

The boys managed to hold up the plane by means of the strong rail until the pilot crawled out.

“Anyone with you?” demanded Frank.

The pilot, struggling to his feet, shook his head. The boys released their grasp on the rail and the wreckage subsided again with a crash.

The pilot came forward. The boys noticed that he lurched slightly as he walked and that he staggered as he came up to them. His uniform was torn and he had a few scratches across his face, but otherwise he did not appear to be badly hurt.

“How are you feeling?” Joe asked him.

Swaying from side to side, the pilot confronted them in silence. His face was flushed.

“Narrow escape,” he muttered. “Mighty narrow escape.” He turned and looked at the wrecked plane, and hiccuped.

“What happened?” asked Frank. “Engine trouble? Or did you run out of gas?”

“I dunno,” answered the pilot thickly. “I dunno what happened. It wasn’t my fault. All the fault of them fellows in the car.”

“Fellows in a car?”

“Yes. Couple of fools in a car ahead of me. I wanted ’em to stop and they wouldn’t. They rushed right ahead and got in my way. Thought I’d scare ’em and make ’em stop, but they kept on going. Then I found I couldn’t get back in the air again—flying too low—it was all the fault of those fools in the car.”

Frank and Joe glanced at one another significantly. Clearly, the man was referring to them. And it was just as clear that the pilot had been drinking.

“We were in a car,” said Frank. “If you think we’re to blame for your accident you’re badly mistaken. You mighty near cost us our lives. We had to get off the road or you would have crashed on top of our car.”

The pilot turned and looked at the boys, an ugly expression in his bloodshot eyes.

“You were in the car, eh?” he shouted. “You’re the fellows that are to blame for this crack-up!”

“It was your own fault.”

“Wasn’t my fault. You fellows wouldn’t stop. I was afraid I was going to hit you. That’s why I lost control of the plane.” The pilot was working himself up into a temper. “You’ll pay for this, let me tell you. My plane is wrecked and I was mighty near killed just because a couple of fool boys didn’t know enough to stop.”

Frank and Joe Hardy stared at the man in amazement. The injustice of the charge passed belief. They were just about to reply angrily when they heard voices and saw men hurrying down the road toward them. A number of farmers in the adjacent fields had witnessed the accident and had lost no time in hastening to the scene.

“What happened? Anybody killed?” demanded one man, as they came up.

“The plane is wrecked. The pilot escaped,” explained Frank.

“No thanks to you young fools,” snarled the pilot. He turned to the farmers. “I’m lucky to be alive. I was trying to make a landing on the road and these young idiots in their car kept racing ahead of me so I couldn’t come down. I lost control of my machine and it’s wrecked.”

The farmers looked gravely at the Hardy boys. Frank laughed.

“I think you’d better wait until you sober up,” he told the pilot, “before you make any charges like that. You haven’t any business being in an airplane when you’re drunk.”

“Who says I’m drunk?” demanded the pilot belligerently. He clenched his fists and stepped forward. “My airplane is wrecked and I’m going to hold you young fools responsible.”

“You can’t blame us for this smash-up!” exclaimed Frank Hardy. “Why, that’s absurd! We were on the road, where we belonged. If you wanted to land, you should have landed in a field. There’s plenty of room.”

“I’ll land my plane wherever I please,” raged the pilot.

“Why pick on us?” asked Joe. “We did our best to get out of your way. I think you deliberately tried to run us down.”

“Never mind. You’ll hear more about this affair. I’m going to report this to the air mail service and they’ll come on you for damages.”

“Try to get ’em,” returned Frank.

A lanky farmer stepped forward.

“I saw the whole thing from the top of the hill,” he said slowly. “If I was you, Mr. Airplane Man, I wouldn’t try to collect no damages from these lads.”

“Why not?”

“Because they wasn’t to blame for the accident. The whole thing was your own fault. And, by jing, if you do try to blame them they can count on me for a witness to prove that they did their best to get out of your way. They was ridin’ peacefully along the road, and then you come swoopin’ and bouncin’ out of the sky and come slap down on the road where you shouldn’t be. You airplane fellows give me a pain. You’ve got the whole sky to move around in, and yet you think you have a right to chase people off the earth too.”

“Is that so?” sneered the pilot. “Well, you’ll have a chance to give your evidence, seeing you know so much.”

“I’m glad of that, Giles Ducroy,” said the farmer. “I’m glad I’ll have a chance to give evidence, for then I can tell ’em how drunk you were when you crawled out from under the plane.”

This shot told.

“I’m not drunk,” stormed Ducroy. “I’m nervous.”

“You must have a pretty bad case of nerves to make your breath smell so strong,” rejoined the farmer calmly. “I’ll bet the air mail service won’t keep you on very long after this, when they hear what I’ve got to say.”

The pilot turned his back.

“I haven’t got time to bother with you. It’s these boys I’m dealing with. I warn you,” he said, glaring at the Hardy boys, “you haven’t heard the last of this. There’s going to be plenty of trouble for you.”

Just then there was a roaring and clattering as a huge truck lumbered down the road, bound from the airport. The driver stared at the scene in amazement. Some of the farmers moved the wreckage of the plane out of the road to enable the truck to pass. Giles Ducroy strode forward arrogantly.

“Driver!”

“Yeah?”

“There are some bags of air mail in my plane. I want you to bring them to Bayport.”

“Who says so?” asked the driver calmly.

“I do. I’m pilot of this plane.”

The driver regarded the wreckage.

“Looks like you made a pretty good job of the crack-up,” he said finally.

Some of the bystanders grinned. Giles Ducroy flushed angrily.

“No nonsense about this,” he snapped. “It’s my duty to see that the mail bags reach the city.”

The truck driver sighed.

“Why didn’t you bring ’em to the airport in your plane?” he inquired.

“Can’t you see? I’ve had an accident.”

“You picked a nice day for it,” observed the driver, glancing up at the sky.

Giles Ducroy lost patience. He went over to the wreckage of the plane and burrowed among the débris until he found the mail bags. These he hauled forth and tossed into the truck.

“There!” he said. “Get them to Bayport as quick as you can.”

“Yes, Commander!” said the truck driver, with an elaborate salute. “The air mail must arrive on time. If I run out of gas I’ll come down in a parachute.” And the big truck lumbered off.

This exchange of witticisms, in which Giles Ducroy had come out second best, judging by the snickers of the farmers who were now crowding about, did not leave the pilot in a very good temper. He stormed into the middle of a group of men who were examining the wreckage, ordered them to stand back, and promised all sorts of dire penalties if anyone touched the airplane until he returned from the airport.

“As for you,” he said, turning to Frank and Joe Hardy before he stalked away, “you’ll hear more about this. You’re to blame for the whole business and I’m going to see that you suffer for it.”

He went away, walking rather unsteadily down the road.

The lanky farmer who had befriended the boys came over to them.

“A man like that oughtn’t to be allowed in charge of a plane,” he said gravely. “I’ll bet if the air service people knew about him being drunk he wouldn’t hold his job two seconds.”

“Do you think he can make trouble for us?” asked Frank. “It wasn’t our fault that he crashed. We did our best to get out of his road, and it was just by luck that he didn’t smash right on top of us. I nearly wrecked our roadster getting out of the way.”

“I saw it,” said the man. “I saw it all from the top of the hill. And it’s just like I told Ducroy. I’ll be a witness for you if there’s any trouble. My name is Jim Perrin and people around here know my word is as good as my bond. You lads were no more to blame for that smash-up than I was, and I’ll tell ’em so.”

“It’s mighty good of you, Mr. Perrin,” said Frank gratefully. “If we have any trouble about this matter we’ll certainly call on you.”

“Be sure you do. I’ll help you all I can.”

The farmer went back toward the wreckage. Frank and Joe decided that their trip to the airport might as well be called off for the time being, as they had no desire for a further encounter with Giles Ducroy. So they went back to the roadster and extricated it from its position among the rocks, backed it out into the highway and headed toward Bayport again.

In spite of Jim Perrin’s reassuring words, the lads were disturbed.

They had no idea how far Giles Ducroy might go and they realized that the man would certainly stretch the truth in order to clear himself with the airport officials. Like most boys, they believed that a man in uniform was vested with powers beyond that of the average citizen and they reflected that the officials might be more inclined to believe Giles Ducroy’s word than theirs.

“I think we’d better tell dad about this,” said Frank. “We know we aren’t to blame, but this thing might be serious if Ducroy makes any charge against us.”

“Good idea,” replied Joe.

When they reached home they ran the roadster into the garage, then went into the house. Fenton Hardy was working in his study, but he put aside his papers when the boys came in and looked up at them with an inquiring smile.

“What’s the matter?” he asked. “You both look as if you have something on your minds.”

“We have,” said Frank.

“Been in an accident with the car?”

“There was an accident, but we weren’t in it. We saw an airplane crash and we’re blamed for it.”

Mr. Hardy looked serious.

“How on earth could you be blamed for an airplane smash when you were in your roadster?”

Frank then explained the circumstances and told how they had been obliged to take refuge in a lane in order to avoid the descending plane.

“It certainly wasn’t our fault,” he concluded. “We might have been killed if we hadn’t reached the lane in time.”

“You say Ducroy was drunk?”

“He had been drinking. We could smell liquor on his breath.”

“I don’t think he’ll get very far if he tries to lay any charges against you,” said the great detective. “The post office authorities won’t be very easy on him if they discover he had been drinking. And, then, you have this witness, Mr. Perrin. I’m inclined to think they’ll accept his word about how it happened.”

“I suppose we’ll just have to wait and see what Ducroy does,” said Joe.

“Perhaps I can fix things up,” said Mr. Hardy. “I happen to have a good many friends in the postal department. I cleared up a big mail robbery here a few years ago and they appreciated it. I’ll go down right away and have a talk with some of the officials and I’ll try to explain things to them. Don’t worry too much about it.”

“That’s mighty good of you, Dad,” said Frank.

“I’ll say it is!” chimed in Joe.

“Well, I certainly can’t see my sons accused of wrecking an airplane when they didn’t have anything to do with it,” said Mr. Hardy warmly. He got up and reached for his hat. “I’ll go and see what can be done about it right away.”

The airplane crash was a front-page feature in the newspapers of Bayport for several days thereafter, and the Hardy boys learned that the post office department was conducting an investigation into the cause of the affair.

Several reporters called on Frank and Joe Hardy to learn their version of the accident, and although the boys told exactly how the crash occurred, they were disturbed to find that considerable space was given to Giles Ducroy’s account. Ducroy was not backward in laying the blame upon the Hardy boys.

“My plane cracked up simply because I was trying to avoid hitting the car,” he said, in an interview. “The boys deliberately drove their roadster ahead so that I was unable to find a landing place until it was too late. They confused me so much that the accident was the result.”

All this looked very bad in cold print, and one of the newspapers hinted that the post office department might take action against the boys if Ducroy’s story was upheld.

“Don’t worry about it,” Fenton Hardy advised. “Don’t let it be on your minds while you are writing examination papers.”

This counsel was sound. The lads were busy writing their final examinations and upon the result would depend their graduation from the high school that year. If they failed, it would mean another term, and a year’s work wasted.

Both Frank and Joe had studied hard and were well up in their work. Under ordinary circumstances they would have had little doubt of the outcome, but with the Ducroy affair on their minds they could not concentrate on their studies as well as they might have done otherwise. Frank shook his head mournfully when the boys left school the afternoon of the geometry examination.

“How do you think you made out?” he asked Joe.

“Not so good.”

“I’m sure I failed.”

“It was a tough exam. Everybody says so.”

“I know it was tough, but I couldn’t help thinking of the trouble we’ll be in if the post office people decide we’re to blame for that accident.”

“It was in my mind too,” Joe admitted, “Still we know it wasn’t our fault.”

“Of course it wasn’t. But the chances are that they’ll believe Ducroy, seeing he’s one of their own pilots.”

“If they blame us, we’ll fight it. We’ll tell them Ducroy was drunk.”

“Perhaps they won’t even listen to us,” said Frank.

The boys went on down the street toward the downtown section. Joe caught sight of a familiar name in a newspaper headline.

“This looks interesting,” he remarked. When he bought the paper, the two stood on the corner to read it.

Joe whistled softly. The boys read further:

The Hardy boys looked at one another in silence.

“I guess that will clear us,” said Frank finally.

“It doesn’t say so.”

“They can’t very well blame us after that.”

A familiar voice broke in:

“Hi, there! Hear the news?”

The Hardy boys looked up to see Chet Morton, one of their chums, approaching. Chet, too, had a newspaper under his arm.

“We were just reading it,” said Joe.

“It was coming to him,” declared Chet warmly. “I was talking to one of the men at the airport yesterday, and he said Ducroy ought to be fired. He was always drinking. None of them were surprised when he had that crash.”

“I’m sorry he has lost his job,” said Frank, “but I guess he deserved it. If they let him stay on he might get into a serious accident and kill somebody.”

“He mighty nearly killed us,” Joe reminded him. “If I only knew that this meant we were clear of blame I could write the rest of my exams with an easy mind.”

“Don’t worry,” advised Chet. “They won’t blame you chaps. The very fact that Ducroy has been let out means that they didn’t believe his story.”

Suddenly Frank nudged his brother.

“Here he comes now.”

“Who?”

“Ducroy,” whispered Frank.

Joe looked around. Coming down the street he saw the former air pilot. Ducroy’s face wore an angry look and he appeared not to notice the stares and the comments of the people near by.

“Don’t pay any attention to him,” said Joe. “There’s no use looking for trouble.”

But, if the Hardy boys were not going to pay any attention to Giles Ducroy, it soon became apparent that the pilot intended to pay some attention to them. He changed his course and came over toward the three boys.

“Now what’s the big idea?” muttered Chet.

Ducroy blustered toward them. He faced Frank and Joe angrily, brushing Chet to one side.

“Well,” he sneered, “I suppose you’re satisfied now?”

“What do you mean?” asked Frank.

“I suppose you’re satisfied now that you’ve lost me my job?” demanded Ducroy.

“You lost it yourself,” returned Frank. “We didn’t have anything to do with it.”

“You didn’t, hey? It was your fool driving that caused the crash, and it was because of the crash that I got fired.”

“The paper says something different,” said Joe calmly.

“It says I got fired because I was drunk, and I was as sober as I am now.”

“And you’re not any too sober now, either,” Chet reminded him sweetly.

Ducroy turned to him. “You keep out of this,” he snapped. “This is none of your business. I’ll thank you to keep your mouth shut.”

“Seeing you ask me so nicely, I will.”

Ducroy turned to the Hardy boys again. “I’m not through with you two yet,” he said. “I may have lost my job, but I’m going to get some satisfaction, anyway.”

“How?” asked Frank.

By way of reply, Ducroy drew back his right arm and lashed out suddenly. His fist struck Frank in the face and sent the youth staggering back. The blow had come so abruptly that he had no chance to defend himself.

But Joe, when he saw his brother attacked, lost no time in getting into action. He plunged at Ducroy without hesitation and planted a swinging blow on the pilot’s right eye, completely closing it. Ducroy gave a yell of pain and struck at Joe, but the blow was wild.

Frank recovered himself.

“Let me handle this,” he said to his brother. And with no further ado he advanced on Ducroy.

The pilot swung at him, but Frank ducked, came in, and stung Ducroy’s face with an uppercut. Ducroy was bigger than Frank and considerably heavier, but he was far from being a scientific fighter, relying chiefly on bull-like rushes and ponderous swinging blows that would have done damage had they landed, but seldom did. Ducroy rushed Frank back across the pavement, his heavy fists swinging, but Frank backed away, ducking and dodging, watching for an opening.

It soon came.

Ducroy swung so wildly that he left himself completely unprotected. Frank’s fist shot out. The blow caught Ducroy directly on the point of the jaw, and he went down in a heap.

“Is that enough?” asked Frank.

A crowd had collected, and Con Riley of the Bayport police force hastened forward.

“What’s all this?” he demanded. “Fightin’ on the streets? What’s the trouble?”

Frank turned away. “Just a little argument,” he explained. “This man hit me first and I had to hit him back.”

“That’s right,” chimed in Chet Morton. “I saw it all. I can prove it.”

Giles Ducroy got slowly to his feet and Riley seized him by the collar.

“I got a good mind to run you in,” said the officer. “What business have you got hittin’ a lad half your size?”

“I don’t want to lay any charge against him,” said Frank. “Better let him go.”

Con Riley looked dubious. Then he released his grip on Ducroy’s collar.

“Well, seein’ you ask it,” he said. Then he glared at Ducroy. “Take yourself out of here!” he ordered sharply. “If I catch you makin’ any disturbance on the street again it won’t go so easy with you.”

Giles Ducroy lurched away, muttering and defeated. Con Riley then turned his attention to the crowd and dispersed the bystanders with a wave of his stick. “Move on!” he ordered. “Move on out of here.”

The crowd scattered.

The Hardy boys and Chet Morton continued their journey down the street. Chet was warm in his praise of the artistic manner in which Frank had dealt with the bully.

“I’ll bet his jaw is sore for a week!” he declared.

“I hate a row like that,” said Frank. “Dad would be angry if he knew we were mixed up in a common street fight.”

“You couldn’t help it. You didn’t start the fight. It was all Ducroy’s fault,” said Chet. “He struck you first. Boy, that was a nice pasting you handed him!”

But Frank remembered the vindictive look in Ducroy’s face as the beaten man slunk away.

“I don’t think we’ve heard the last of this, by any means,” he said.

It was not until the next evening that the result of the investigation into the airplane crash was officially announced. Then, to the joy of the Hardy boys, they learned that the authorities held them blameless for the accident.

The report ran, in part:

Frank danced an impromptu jig. “Hurrah!” he shouted. “That takes a load off my mind.”

“I’ll bet dad put in an oar for us,” said Joe happily.

“Shouldn’t be surprised. Let’s go and ask him.”

When they entered Fenton Hardy’s study, the detective smiled at their evident delight.

“What’s happened?” he asked. “Have you fallen heir to a fortune?”

“Better than that. The post office people have announced that we aren’t to blame for that plane wreck,” declared Frank. “We’ve been worrying our heads off about it.”

“Did you help, Dad?” asked Joe.

“Oh, I may have said a few things to the inspector,” observed Mr. Hardy. “He is an old friend of mine and I have done him a few favors in my time. It really wasn’t necessary, because I don’t think they would have blamed you in any case. But it prevented them from being fooled by Ducroy, anyway.”

“That was certainly mighty fine of you. Dad!” exclaimed Frank. “I don’t know how we can thank you.”

“I know,” said their father. “You can go back to school to-morrow and dig into those examinations and graduate this year.”

“We’ll do our best,” they promised.

“The exams won’t be so bad, now that this worry is off our minds,” added Joe.

For the rest of the week the Hardy boys attacked their final examinations with such determination and enthusiasm, unmarred by any worries about the airplane accident, that when they handed in their final papers they knew that if they had obtained passing marks on the papers written earlier in the week there was little doubt of the final outcome.

“But that’s just the trouble,” groaned Joe. “I was so worried when I wrote those first papers that I’m sure I didn’t get by.”

“Forget it,” advised Frank. “The exams are over and we can’t change the papers now. We’ll just have to be patient and wait for the results.”

“I wish I knew them now,” said Chet Morton. “If I don’t pass this year, my dad will flay me alive. I might as well pack up and head for Alaska if I don’t get through. What are you fellows going to do, now that school is over?”

“Wait for the results,” returned Frank. “If we pass, I think dad wants us to go to college and we’ll have to start making our plans.”

Jerry Gilroy, another chum of the Hardy boys, sauntered up.

“How about you, Jerry?” asked Frank, “What are you going to do now?”

“I have a job,” announced Jerry calmly.

“Already?” the others exclaimed enviously.

“I start work Monday as a reporter for The Banner.” Jerry stuck out his chest and pulled his hat brim down over one eye.

“That’s a good job,” said Tony Prito, who joined the group at that moment. “You’ll be able to get into all the shows in town for nothing and get through the police lines at all the fires.”

“Well,” said Jerry doubtfully, “just at first they’re putting me at work writing up obituaries and real estate deals. But I’ll soon work my way up,” he added hastily.

Tony Prito announced that his parents had decided on a college course for him and that Phil Cohen was bound in the same direction.

“Looks as if the old gang will be broken up by next fall,” said Joe glumly.

“That’s true,” agreed Chet. “I think we all ought to get together as soon as we know the results of the exams and have one big party to celebrate.”

“A picnic!” exclaimed Frank.

“Good idea!” declared Jerry Gilroy. “I’ll write it up for the paper.”

“Where shall we have the picnic?” asked Tony. “Beach Grove?”

“Beach Grove is the only place for a picnic. We’ll have the whole graduating class,” Frank said. “The girls, too.”

“I don’t know about that,” demurred Chet, who did not care for girls.

“Go on with you. If we have a class picnic we can’t leave the girls out. Anyway, they’ll be sure to bring along lots of eats.”

“Oh, I forgot about that,” said Chet, who had a weakness for food. “By all means, we must have the girls along.”

“In the meantime, Jerry, keep your eyes open around your newspaper office and see if you can’t get a look at the examination results when they’re sent in for publication,” Frank suggested. “They’ll appear in the paper first, and if you get on the good side of the city editor he may let you have a look at them.”

“And phone us right away,” added Chet.

Jerry promised to keep on the lookout for the examination results.

Frank’s suggestion of a picnic met with the instant favor of the other members of the graduation class who were enthusiastic over the idea. They all realized that within the next few months the class would be scattered far and wide and that it would probably be their last opportunity of being all together.

Then they settled down to the tedious business of awaiting the all-important results. Two days passed, with no word from Jerry Gilroy, who had extracted a promise from his city editor that he would be shown the list as soon as it reached the office. The Hardy boys and their chums bided their time with such patience as they could muster. Frank and Joe went out on Barmet Bay in their motorboat, The Sleuth, and explored the countryside in their roadster.

On Thursday morning the boys were in the gymnasium in the barn back of the Hardy home. Chet Morton was sitting in a window munching at an apple, as usual. Biff Hooper was drumming away at the punching bag. Tony Prito was practicing some complicated maneuvers on the parallel bars, while Phil Cohen and Joe Hardy were engaged in a spirited wrestling match. Frank was busy trying to repair a broken baseball bat, with small success.

“Somebody calling you, Frank,” said Chet, glancing out the window.

Frank looked out. Aunt Gertrude was standing in the back door, beckoning to him.

“You’re wanted on the telephone,” she called.

“It must be from Jerry!” shouted Frank.

The others stopped their activities instantly. Frank almost tumbled down the stairs in his anxiety to reach the house in the quickest possible time. The other boys crowded to the window. They saw him disappear into the house. He seemed to be away for a long time.

“Bad news, I’m sure of it,” moaned Chet.

“Good news, I’ll bet a cookie,” said Joe, trying to be cheerful.

After a while they saw Frank come out of the house. His shoulders drooped. He walked slowly.

“What’s the verdict?” clamored Chet.

Frank looked up, shook his head mournfully, and sighed. They heard him coming up the stairs.

“I knew it,” Chet groaned. “We’ve all failed.”

When Frank came up into the gymnasium they crowded around him. He looked as though he had lost every friend he had in the world.

“For the love of Pete, don’t keep us in suspense!” demanded Tony. “Was it Jerry? What did he say?”

“It was from Jerry,” admitted Frank heavily. “Well, fellows, I don’t know how you’re going to feel about it, but as for me——” he shook his head again.

“Back to the high school for another year, is it?” asked Joe solemnly.

“Don’t take it too badly, fellows. Of course, we all knew the exams were harder than usual.”

“Yes, they were tough,” admitted Chet. “But, hang it all, didn’t some of us get through? I was sure I’d failed, but I thought the rest of you would make it.”

“The results are out,” said Frank. “I know you’re going to feel bad about it, but every one of us—every one, mind you—passed!”

“What?” they roared.

Frank turned a handspring.

“We all passed!” he yelled, in delight. Then he sat down on the floor and laughed at the expression on their faces. “Boy! didn’t I throw a scare into you?”

Biff Hooper hurled a boxing glove at him. Phil Cohen seized Tony Prito around the waist and danced about in glee. Chet threw away the core of his apple and stood on his head. Joe vaulted over the parallel bars. Pandemonium reigned.

School was over at last!

“And now,” shouted Frank, “for the picnic!”

Preparations for the picnic at Beach Grove on the following Saturday were in full swing during the next few days. All the members of the graduation class at Bayport High were enthusiastic, and the girls were busy baking cookies and cakes. From the standpoint of Chet Morton, at any rate, the success of the outing was therefore assured.

“As long as there’s plenty of food, it will be a good picnic,” he said.

Callie Shaw, who was Frank Hardy’s particular favorite among the girls of the class, admitted that she felt sad at the prospect of seeing “the crowd” broken up at last.

“We had some good times at High. Somehow, I wish now that we had all failed so we could go back for another year.”

“You didn’t feel like that when you were writing the math exam,” Iola Morton, Chet’s sister, reminded Callie.

“No. I suppose if I did go back I’d be grouching about the work all over again,” laughed Callie. “I’m glad we’re going to have the picnic, though. It will be nice to be all together again for once before the class is scattered.”

“There won’t be many of the gang left around town by next fall,” said Frank. “What with some going to college and others going to work, the class will be pretty well broken up by then.”

“I hope we’ll get good weather for the picnic,” ventured Joe.

“The class had good luck on the exams,” Iola reminded him; “so we should have good luck with the weather.”

Iola’s optimism was justified. When the day for the picnic dawned the sky was cloudless, the day was warm and clear. Mrs. Hardy had prepared a big basket of good things for the Hardy boys to take with them, and they stowed the basket in the roadster along with their bathing suits and baseball gloves. They had arranged to call for Callie Shaw in the car, while Iola was to go with Chet in his roadster.

It was to be a real picnic—“not one of these afternoon teas,” as Chet expressed it. All members of the class had been notified to meet at Beach Grove by ten o’clock in the morning and when Callie and the Hardy boys reached the grove they found a dozen others already on hand. Chet arrived a few minutes later with Iola and Biff Hooper, whom he had picked up on the road, and by half past ten the crowd was complete.

Beach Grove was just off the Shore Road and extended to a sandy beach on the shore of Barmet Bay. There were many paths through the woods, a grassy meadow which was ideal for baseball games and races, and the park keeper had granted them permission to use a little building in the grove where a stove and kitchen facilities were installed. The boys lit a fire and busied themselves bringing up driftwood from the beach, while some of the girls settled down to preparing lunch and opening up the numerous baskets at their disposal.

The Hardy boys and the other lads went down to the beach for a swim before lunch, and had some fine sport on an improvised raft which they took turns in defending against all comers. Chet Morton became unduly ambitious and tried to improvise a sailboat out of a plank and an old piece of tarpaulin he found on the shore, but the sailboat came to grief and tipped Chet into the water, to the hilarious delight of his companions.

By the time the swim was over and the boys returned to the Grove they had developed lusty appetites for lunch, and there were loud cheers when Callie, as chief cook, hammered a tune on a tin plate with a poker, announcing that the meal was ready. There was hot coffee, heaping bowls of baked beans, stacks of sandwiches, plates of potato salad, and cake and fruit without end. The boys and girls sat beneath the trees and ate from tin plates until they could eat no more.

Chet, alone, looked discontented when lunch was over.

“What’s the matter with you?” asked Tony Prito. “Didn’t you like it? I thought it was the best meal I ever tasted.”

“The meal was all right,” said Chet dolefully.

“Then why are you looking so glum?”

“I never have any luck,” confessed Chet. “Something always goes wrong.”

“Didn’t you get enough to eat?” asked Callie anxiously. “There is a lot more potato salad.”

“No, thanks. I don’t think I could eat any more potato salad—not just now, at any rate. It was very good potato salad but I couldn’t eat any more right now. Maybe in an hour or so—oh, well, it doesn’t matter.”

“If the meal was all right and you got enough, what’s all the trouble?” asked Frank Hardy.

“I saw you take three helpings of beans,” added Joe.

“That’s why I feel so badly.”

“Got a tummy-ache?” asked Iola solicitously.

“No. But, you see, I liked the beans so well that I took two helpings after the first one, and I liked the potato salad so well I took two helpings of that, extra, and then I saw some sandwiches I liked real well and I ate about a dozen of them, and then somebody passed around angel food cake so I ate that, and then I didn’t have any room for anything else.”

“I think you did very well,” remarked Jerry Gilroy. “I don’t see where you have any kick coming.”

“I like chocolate cake. It’s my favorite cake,” declared Chet gloomily.

“There was plenty of chocolate cake,” said his sister. “There are two chocolate cakes left right now.”

“Save ’em for supper,” advised Chet. “That was the big trouble. I like chocolate cake so well that I feel bad because I was so full by the time it reached me I couldn’t eat any.”

The others looked at one another helplessly.

“What can you do with a fellow like that?” demanded Phil Cohen. “He’s never satisfied.”

“I think he needs exercise,” said Iola threateningly.

“Now, don’t!” pleaded Chet, who had found a soft spot beneath a shady tree and was preparing to go to sleep.

“Maybe you boys don’t know it,” said Iola, “but I do. Chet is ticklish!”

“Don’t, Iola!” clamored the victim.

But Iola advanced on her brother and tickled him until he yelled for mercy, whereat the others, delighted at the exposure of this secret, pounced on the luckless Chet and rubbed his ribs until he was forced to make his escape. They chased him through the meadow, shouting with laughter, and back and forth among the trees until he could run no longer.

“It’ll help him digest those three helpings of beans and potato salad,” said Iola, without sympathy.

Having concluded their attentions to Chet, the classmates organized an impromptu program of sports, with races, a ball game and a blindfold boxing match between Biff Hooper, Jerry Gilroy, Phil Cohen and Tony Prito, which ended without casualties. Biff, who prided himself on his boxing ability, wandered away from the others and tackled a large tree, under the impression that it was Jerry. After dealing a dozen terrific blows without knocking out the enemy he tore off the blindfold and then looked very sheepish.

Most of the others went swimming during the afternoon, but the Hardy boys had decided to take advantage of the opportunity and investigate a mysterious little cabin at the far end of the grove. They had often been curious about the place, and it was Frank’s suggestion that perhaps the cabin was used as a hiding place for smugglers that prompted their decision to visit the place.

“May we come, too?” asked Callie Shaw, as the two boys were starting off together. She and Iola had remained behind to clear up the last of the picnic dishes while the other girls went swimming.

“Glad to have you,” answered Frank.

“Come on, Iola.”

The two girls went running across the grass, and the four young people set out down a winding path beneath the trees.

“Where are you going, Frank?” Callie inquired.

“We thought we’d take a walk over to that little cabin at the east end of the grove. Joe and I have often been curious about that place, but we’ve never been near it; so we thought this was as good a chance as any.”

“Oh, this is thrilling!” declared Iola. “Do you think there’s anything suspicious about it?”

Joe shrugged. “Perhaps. It will be fun to look the place over, though. We thought it might be used by smugglers.”

“Smugglers!” exclaimed Callie, stopping. “I’m frightened. I don’t think I care to go after all. I don’t want to meet any smugglers.”

“Nonsense!” laughed Frank. “There wouldn’t be any smugglers around at this time of day, anyway. We’re not sure about the smugglers in any case. Perhaps it’s just a perfectly innocent tumbledown old shack, with nothing strange about it at all.”

Callie gathered up courage and they went forward again. The little cabin was at the extreme end of the grove, and it was some time before they came within sight of it. Finally, rounding a bend in the path, they caught a glimpse of the place among the trees. The cabin had been built in the woods, several hundred yards back from the water.

“Mighty dingy looking cabin, it seems to me,” remarked Iola.

“Why, there are some smugglers now!” exclaimed Callie, wide-eyed. “Don’t you see them, Frank? Down in the bushes. Look, they’re going up toward the cabin!”

Frank called a halt.

“Just a minute!”

He could see three men making their way up a path in the direction of the cabin. The trio were apparently unaware that they were being watched, for they did not look around. For a moment they were hidden by the intervening branches. Then they appeared in view again. One of the men halted in front of the cabin, removed a key from his pocket, and unlocked the door.

The three men disappeared inside.

Frank turned to the others.

“I think we’d better go back,” he said quietly.

“Were they smugglers?” demanded Callie. “Let’s get out of here. They might start some trouble.”

They turned and retraced their steps toward the picnic grounds. Once Joe said:

“Do you know, I’m sure I recognized one of those chaps.”

Frank flashed him a warning look.

He did not want to alarm the girls, so he had said nothing. But Frank, too, had recognized one of the men, and he was none other than Giles Ducroy!

When the Hardy boys and the girls got back to the picnic grounds, the boys excused themselves and drew away to one side, while the girls went down to join the swimmers.

“I think we ought to go back there,” said Frank quietly.

“Why? Did you recognize any of them?”

“Did you?”

“I thought one of them looked mighty like Ollie Jacobs,” said Joe. “He’s a pretty shady customer, as you know. I’ve heard of more than one bad business he has been mixed up in around Bayport.”

“Ollie Jacobs, was it? Then the other fellow must have been Newt Pipps! He is always hanging around with Jacobs. They’re a bad pair.”

“Who was the other fellow? I didn’t get a good look at him.”

“I did,” returned Frank. “He was Giles Ducroy.”

Joe whistled in amazement.

“So that’s who Giles Ducroy is mixed up with now! I wonder what they’re doing down in that old cabin?”

“We’d better go and find out. We can get up to the back of the place without being seen, and perhaps we can overhear what they’re saying.”

“Come on. It’s worth trying, anyway. I’m interested.”

The boys hurried off down the path. Once Joe glanced up at some lowering clouds that had gathered above the trees.

“Looks like rain,” he remarked.

“It may hold off for a while. It won’t stop me from finding out what that gang is up to.”

“Not if I know it,” declared Joe.

When the boys came within sight of the cabin they proceeded more cautiously. They did not come out into the open, but edged their way around through the trees until they came to the rear of the little building.

“There’s an old road near here,” whispered Frank. “Perhaps that’s how they reached the place.”

“I can see it from here. And look—there’s a car! It’s parked under the trees.”

“That explains how they come to be here. They’ve probably arranged a meeting. There’s some funny business on foot, I’ll be bound.”

Cautiously the brothers went on through the undergrowth. It was fortunate that bushes grew within a few feet of the back of the cabin, so the boys were able to make their way near enough to overhear the conversation of anyone who might be within without danger of being seen themselves.

As they pressed close against the logs of the cabin they could hear a murmur of voices. They soon found a convenient chink in the logs where they could peep through. There, in the dimly lighted interior of the building, they saw Giles Ducroy, Ollie Jacobs, and Newt Pipps seated about a rude table, with a bottle and glasses before them.

“I tell you,” Ducroy was saying, “I know what I’m talking about. I’m giving you fellows a chance that lots of other men would jump at.”

“It sounds good,” admitted Jacobs, a short, ill-favored man with squint eyes. “But it’s mighty risky.”

“Nothing venture, nothing gain,” said Ducroy, taking a swig from the bottle.

“That’s true,” said Newt Pipps. “But I’m not anxious to get a bullet through me.”

“Bullets, nothing!” scoffed Ducroy. “We’ll get away with this as smooth as silk.”

“Maybe,” demurred Jacobs. “You say the money is sure to be there, all right?”

“I know it will be there. I wouldn’t tell you fellows about it if I wasn’t sure.”

Newt Pipps shrugged. “Well, I’m as brave as the next man,” he said, “but this is a mighty big job. It’s bigger than any I’ve ever tackled yet, and I can’t say I like it.”

“The bigger the job, the bigger the profit,” remarked Ducroy.

“Yes, and the bigger the risks, too.”

Ollie Jacobs looked around uneasily.

“Don’t talk so loud,” he said. “If anybody hears us, we’re done for.”

“Who could hear us?” demanded Ducroy, who was evidently half intoxicated. “That’s why I picked this cabin for a meeting place. There’s nobody within miles.”

“Oh, yes there is,” Jacobs answered. “A bunch of high school kids are having a picnic over in Beach Grove, and that’s not very far from here.”

“I thought I saw somebody over among the trees when we were coming in here,” said Newt Pipps.

“You did?” said Ducroy. “Why didn’t you speak up?”

“I might have been mistaken.”

“If you think there’s anyone around, go and take a look around the cabin. A person would have to be mighty close to the place to hear us talking.”

Then, to the horror of the Hardy boys, Newt Pipps got up from his chair, rather unsteadily.

“That ain’t a bad idea,” he remarked. “I’ll just do that.”

He moved over to the door, opened it, and stepped outside.

Frank and Joe had no time to lose. They knew that in another moment Newt Pipps might come walking around to the back of the cabin. They drew back quickly, yet cautiously, seeking the shelter of the undergrowth near by.

The bushes were small and afforded little cover, yet they did not dare move back farther for fear of being heard. So they crouched down as far as possible. They were not a second too soon. Scarcely had they flattened themselves in hiding than they heard heavy footfalls from the side of the cabin.

They were so poorly hidden that they could plainly see Newt Pipps as he came around the corner. But Pipps had been drinking and he had evidently little expectation of seeing anyone around. He did not search in their direction, but contented himself with a casual glance, then turned and went back again.

Frank breathed a sigh of relief.

“That was close!” he whispered.

“I’ll say it was,” affirmed Joe.

The Hardy boys waited until they heard the cabin door slam again. Not until then did they emerge and creep forward to the rear of the cabin once more.

Newt Pipps was sitting down at the table.

“Satisfied?” asked Giles Ducroy curtly.

“There’s no one around. Still you can’t be too careful,” said Pipps.

“That’s true,” agreed Jacobs. “Never know when somebody may be hanging around.”

“Well,” snapped Ducroy, “I can’t stay here all day. I’ve made a proposition to you men and I want to know what you’re going to do about it.”

Ollie Jacobs and Newt Pipps looked at one another.

“What do you say, Ollie?”

“I don’t know. There’s a lot of money in it for us, all right. And I could use some cash right now. I’m pretty near broke.”

Giles Ducroy leaned forward and pounded his fist on the table.

“There’s ten thousand dollars or more apiece in it for us,” he declared. “Where else could you make ten thousand dollars as easily, I’d like to know.”

“It’s easy money,” admitted Newt. “But it’s dangerous.”

“And we might get shot,” added Ollie.

“I’m taking that chance the same as you,” Ducroy answered. “Well, hurry up. I can’t wait here all day.”

“Ten thousand looks mighty good to me,” said Newt Pipps. “But I ain’t anxious to get shot earning it, for then it wouldn’t be any use to me.”

“Same here,” demurred Ollie Jacobs.

Just then there was a low growl of thunder overhead. Raindrops began pattering on the cabin roof. Frank and Joe Hardy looked up and saw that the brooding storm was already breaking.

“It’s starting to rain,” said Ducroy. “I want to get back to the city before the storm turns that road into a mud-hole. Can’t you make up your minds?”

“I’ll tell you what we’ll do,” said Ollie Jacobs, finishing the bottle. “Newt and me ought to talk this over a little more. There’s a lot of money in this job, but there’s a lot of risk too, and I want to make sure it’s safe.”

“Of course it’s safe!” raged Ducroy. “You’ll never make an easier ten thousand in your life.”

“That’s letting you tell it.”

“I think Ollie is right,” said Newt. “We’ll talk it over and let you know later.”

“When? I can’t wait long, you know. I’ve got my own plans to make yet.”

“We’ll let you know to-night,” declared Jacobs, getting up.

“All right,” grumbled Giles Ducroy. “But don’t take any longer. Come on, now. It’s starting to pour. I want to get back to town.”

The three men left the cabin. Rain was now falling on the roof in a steady downpour. The Hardy boys looked at one another, puzzled.

“I wonder what mischief those three are up to?” said Frank, as the brothers hurried back into the shelter of the grove.

The clouds were black overhead and the rain was pouring steadily as the Hardy boys hastened back up the path toward the picnic grounds. Once under the trees they were partly sheltered from the rain but in the open spaces they were thoroughly drenched. Thunder rolled continuously, lightning flashed, and the rain came in sheets.

“This ends the picnic,” panted Joe, as they ran back.

“It sure does. Everybody will be soaked.”

The trees were threshing and sighing in the wind. There was a vivid flash of lightning followed immediately by a crash and a clap of thunder.

“Must have hit a tree,” said Frank.

When they came in sight of the picnic grounds, Frank saw that he had guessed correctly. Only a few yards away from the cook-house, a great oak lay prone on the ground, a jagged fragment of the trunk sticking up out of the earth. The trunk had been sundered by the lightning and the great tree had been struck to earth.

Inside the cook-house, the boys and girls of the graduating class were huddled together. Many of them were badly frightened, for the lightning flash had come unpleasantly close, and the falling tree had missed their refuge by a scant few feet.

As Frank and Joe came racing across the sloppy ground, a cheer went up.

“Here they are!”

“Here come the Hardy boys!”

“At last!”

“Where have you two been?” shouted Chet Morton, as they dashed up onto the veranda, their clothes dripping wet. “We’ve been worried sick. Thought you’d got struck by lightning.”

“Looks as if you people were nearer to being struck than we were,” replied Frank, looking ruefully at his drenched garments.

“We’ve been awfully worried,” said Callie Shaw, pressing forward. “When the storm began, everybody gathered here except you and Joe, and we had no idea where you were.”

“Oh, we were just exploring around,” said Frank. “No harm done, except that we’re mighty wet.”

“No harm done!” exclaimed Iola Morton. “How about our nice picnic? It’s all spoiled now!”

“Well, we were nearly ready to go home anyway,” observed Chet. He turned to the Hardy boys. “Well, you two chaps missed the best display of fireworks I’ve seen since last Fourth of July.”

“Looks as if you had a mighty narrow escape,” said Joe.

“We certainly had. There was a flash of lightning that seemed to miss us all by about two inches, then the loudest crash of thunder I ever heard in my life, then a tearing and crackling, and we saw that big tree topple over.”

“It seemed to be coming right down on top of the house,” said Callie.

“We thought we were done for. If that tree had ever hit the roof we would have been crushed to death. And that would have spoiled the picnic for sure,” added Chet.

The very real danger they had been in and the storm had dampened the spirits of the graduating class, and when the rain finally began to die down there was not a dissenting voice when Frank Hardy suggested that they make a dash for the cars. Hastily packing up the baskets, they left their refuge and ran across the grass to the cars parked out by the gate. Everyone found a place, and within a few minutes the picnic grounds were deserted.

The lull in the storm had been only temporary. Rain came down in torrents before they had gone more than half a mile along the Shore Road, and some of those in open cars who had not taken the precaution of putting up the tops, received a second drenching. Frank and Joe, in their roadster, accompanied by Callie Shaw and Iola Morton, were more fortunate, and they soon arrived on the outskirts of Bayport without mishap.

The picnic party broke up without further ceremony, the cars scattering in various directions as the boys of the class drove the girls home. Frank and Joe drove Callie to her aunt’s store in Bayport and Iola decided that she would wait there for Chet, who was to drive her home that evening. In their wet clothes, the picnickers presented a sorry sight, but all in all they agreed that they had had a good time which even the thunderstorm could not spoil.

When Frank and Joe Hardy reached home and changed their clothes, their mother was sympathetic.

“It’s too bad,” she said, as she prepared a hot supper for them. “You had all been counting on that picnic.”

“Well, we had half a picnic, at any rate. We can be thankful for that much,” Frank observed. And then, when their mother was in the kitchen, he added to his brother: “I don’t call the day wasted.”

“You mean Ducroy?”

“Yes. We learned that he’s up to some funny business. I’d like to know what it’s all about.”

“Something crooked, I’ll be bound,” declared Joe.

“Ten thousand dollars apiece, he said. That’s a lot of money. I’m sure Giles Ducroy and his two precious friends could never earn that much money honestly.”

“It must be crooked. The big reason Ollie Jacobs and Newt Pipps objected to the scheme was because there was danger in it and they might be shot.”

“Maybe they intend to rob a bank,” ventured Frank.

“I wish we knew. Still, perhaps it was all just talk. They were half drunk, you know.”

“Yes, I thought of that.” Frank shook his head. “Still, now that Giles Ducroy is out of work, he might be turning his hand to some kind of thievery.”

“Do you think we ought to tell dad?” Joe suggested.

“Not yet. After all, those men were drinking and it might have been nothing more than drunken chatter. Perhaps Ducroy was only bragging and trying to make a big fellow of himself by telling them he could help them make so much money. We don’t know what they were talking about in the first place. We’d just look foolish if we went to dad with our story and nothing came of it.”

“He couldn’t do anything, anyway. No more than we can.”

“All we can do,” said Frank, “is to watch and wait.”

“We’ll watch, all right. We’ll try to check up on Giles Ducroy and find out what he’s up to. We have one big advantage—he doesn’t know we overheard what they were saying in the cabin.”

“He doesn’t know we were within miles of the place.”

“I’m puzzled about that conversation. If there was nothing in it,” said Joe, “why did they pick such an out-of-the-way spot to have their meeting?”

“It may have been because of the liquor. It’s against the law to have it,” Frank pointed out. “Perhaps we were only listening in on a drinking party after all.”

“I don’t think so. I have a pretty strong belief that there was more than that behind it. Giles Ducroy and that other pair are a bad combination. When you see those three together it means there is some trouble being hatched.”

Their mother came in just then with the tea things, so the boys turned the conversation to other matters. Mrs. Hardy wanted to know what was next on their program, now that school was over and the class picnic a thing of the past.

“Graduation exercises,” said Frank promptly. “Next week, at the high school.”

“I must get a new dress,” Mrs. Hardy declared.

“You’ll certainly have to get all dolled up to come and see your sons step up for their diplomas,” agreed Joe laughingly. “It only happens once in a lifetime, you know.”

“I’m glad to see you graduate, but in a way I’m sorry,” confessed their mother. “It means you’re growing up and you soon won’t be my boys any longer.”

“We’ll always be your boys, even if we live to be a hundred,” declared Frank, putting an arm about his mother’s waist.

“Have you decided what you want to do after the holidays are over?” she asked. “You know I’ve been counting on having you both go through college.”

The boys looked serious.

“We’ll have to think about that,” Joe said. “Still, there’s lots of time. A whole summer ahead of us.”

“Be sure and think seriously about it,” their mother warned. “It is a serious matter. Your whole future will depend on your decision.”

“Maybe by the end of the summer we’ll feel different about going to college,” said Frank. “Just now I’m so glad to be out of school that I never want to see another study book again as long as I live.”

“Me, too,” declared Joe.

Their mother smiled indulgently, and the matter of the boys’ future plans rested at that.

The night of the graduation exercises at the Bayport high school arrived, differing little from similar events in past years but of profound importance to the members of the graduating class and their parents.

Mr. and Mrs. Hardy were there, very proud of their two boys, and Mrs. Hardy beamed with pleasure when Frank and Joe, dressed in their finest clothes and looking very uncomfortable, stepped up to receive their diplomas. Chet Morton was so nervous and embarrassed that he stumbled on the way to the platform and ended by dropping the diploma when it was handed to him.

All the girls looked their prettiest, the boys looked their handsomest, the principal of the school excelled himself in the speech he had made at every graduation for the past fifteen years, various prominent citizens expressed their pride in the young people, and Callie Shaw, as class valedictorian, won the hearts of all by her valedictory address.

There were other numbers on the program, including a violin solo by Iola Morton, an exceedingly vigorous recitation by Biff Hooper, an accordion solo by Tony Prito and—to cap it all—the antics of a burlesque orchestra organized by Chet. In this, Chet was in his element, wearing a fireman’s hat and a huge false mustache. Frank and Joe Hardy, wearing stovepipe hats and red wigs, alternated at a bass drum; Jerry Gilroy, in a coat that reached to his heels, performed upon a saxophone that wouldn’t work and from which Chet produced a string of sausage at the critical moment; Phil Cohen tortured a flute that was capable of but one note. The burlesque orchestra assaulted the ears of the audience for some time, with no music whatever, but with such earnestness that the hearers were doubled up with laughter.

This was the high spot of the program, so far as the boys were concerned, and it ended the graduation exercises. When they left the school that night they all felt a little sad, as they knew they were leaving it for all time, “unless,” Chet Morton said, “they invite us back some day when we’re very famous to address the students on ‘The Secret of Success.’ ”

“In the meantime,” said Frank, “what are we going to do this summer?”

“I’d like another outing,” Joe volunteered.

“Too much excitement for me,” returned Chet. “Last summer we were going to have a nice quiet trip down the coast, and look what happened. We got mixed up with a gang of smugglers and had no end of trouble.”

“It finished up happily enough, didn’t it?” said Frank. “Even if you did get lost!”

“This summer, I’d like to have a nice quiet holiday in a nice quiet cabin, with a good beach, where we can swim and loaf around and eat and sleep and not have anything to worry about.”

“Sounds attractive,” Joe admitted. “Where are you going to find this place, and how can we get there?”

“How about Cabin Island?” suggested Biff Hooper.

The others were thoughtful.

“You’ve had worse ideas, Biff,” said Chet Morton. “Do you think Mr. Jefferson will let us go there?”

Frank laughed.

“Why not? Didn’t we find his missing stamp collection? Didn’t he say we could have the use of the island and the cabin any time we wished? There won’t be any trouble so far as that’s concerned.”

“I think an outing to Cabin Island would be the real thing,” Joe declared. “What do you say to organizing a trip? We can take the motorboats, use Cabin Island as our headquarters, then work out from there so we can go wherever we wish.”

“You have a head on your shoulders,” Chet approved. “When we get tired of camping we can go exploring. When we get tired of the motorboats we can loaf around Cabin Island.”

“Joe and I have the summer free,” said Frank. “After that, we’ll either go to college or go into business with our father.”

“Don’t you know yet?”

“We want to go in with dad,” said Joe promptly. “But he and mother seem bent on having us go to college. I think we’ll have a lot of arguing yet.”

“In the meantime, don’t let it spoil your summer,” advised Chet. “Well, if you want to go on this outing, be sure and count me in. We can dig up some of the other fellows and we ought to have a bang-up good time.”

“You can’t dig up many of them,” came from Joe.

“Why not? Any fellow ought to jump at a chance like that.”

“Well, some of them wouldn’t be allowed to leave home—got to work and all that. And some are on the ball team and have to practice when they aren’t playing a game. And Dick Roylet and his crowd are going on an auto tour.”

“Well, we’ll get somebody—if we go,” put in Frank.

Next day when the Hardy boys told their parents about the outing they had planned, Mr. and Mrs. Hardy glanced at one another.

“Don’t you think you had better be making your preparations for going to college?” suggested Mr. Hardy.

“If you wait too long, perhaps you may not be able to get in,” their mother ventured.

“Do we have to go to college?” asked Frank.

Mr. Hardy looked dubious.

“You know, your mother and I have always had that in mind for you.”

Joe groaned.

“I’ll make a rotten lawyer.”

“And I’m sure I’ll be a pretty punk doctor,” declared Frank. “Dad, won’t you let us go into business with you? We like detective work. It’s the only thing we’ll ever be happy at. Haven’t we done fairly well with the cases we’ve had so far?”

“Yes, you’ve done well. I’ll admit that. Still—I think I’d rather see you go in for something else.”

“Would you want us to go in for something we wouldn’t enjoy?” said Joe. “A person can’t be a success in his work unless he really likes it.”

“That’s true,” returned Mr. Hardy, weakening a little. “Well, I must have time to think it over.”

Frank offered a suggestion.

“Let us go on our outing first, and by the time we come back we can settle the whole thing. We’ll be back in plenty of time to go to college, if you really insist that we go.”

Mrs. Hardy nodded. “I think that’s fair enough, Fenton,” she said to her husband.

“All right, then,” agreed the detective. “We’ll let the matter rest for the time being, and as soon as you boys return from your trip we’ll go into it thoroughly. But you must promise to abide by my decision. I don’t want to send you to college against your will, but I do want to do what’s best for your future.”

“We understand that,” said the boys. “It’s for our own good. But we do want to be detectives.”

Mr. Hardy smiled.

“You seem to have your minds made up, at any rate. Well, let it go at that. Have your outing and enjoy yourselves. Then we’ll settle the whole matter, once and for all.”

However, the lads had little time in which to proceed with their plans for the outing. They did not see Chet Morton that afternoon and the trip was not discussed with any of the other lads they met. Next morning, as they were having breakfast, their father came into the dining room.

“After breakfast is over,” he said, “come into my study. I want to have a little talk with you.”

“We’ll be there.”

When their father had gone, they fell to wondering why he wanted to see them.

“I can’t think of any mischief we’ve been into—except breaking that pane of glass in the garage,” said Joe.

“He wouldn’t scold us for that. I intended to put in a new pane of glass to-day.”

“There’s something in the wind.”

They hurried through the remainder of the meal, anxious to learn the reason for the summons. When they went into the study, Mr. Hardy was reading a long typewritten letter which he placed to one side.

“I’ve been asked to handle a case,” he explained at once, “and I thought maybe you could help me a little. Sometimes you hear of things that I mightn’t learn about. This is a serious case and just now I’m trying to make up my mind how to go about it.”

“What has happened, Dad?” asked Frank.

“I received this letter this morning from the postal authorities, explaining the circumstances. It seems that several bags of valuable mail have disappeared from one of the hangars at the airport near here.”

“Stolen?”

“They couldn’t have disappeared any other way. The mail, as you know, is very carefully guarded. In this instance, the train that was to take the mail into the city was a few minutes late and the sacks were accidently left unguarded. When the train arrived it was found that the mail had disappeared. The matter is being kept quiet for the time being, in the hope that we may get a clue. But so far the whole business seems to be a complete mystery.”

“Haven’t they any idea who stole it?” asked Joe.

“No idea at all. The only men around, so far as they know, were the usual airport officials and pilots. Practically all of them are above suspicion. From the looks of the case, I’m inclined to think some outsider may have been hiding near by, watching his chance, and when he saw the sacks left unguarded he simply seized them and cleared out.”

Frank leaned forward in excitement.

“I think we can help you a little,” he declared. “We may know something about that very robbery.”

“Already?” exclaimed Fenton Hardy, astonished.

Frank and Joe thereupon told their father about their adventure in Beach Grove on the day of the picnic. They told that they had seen Giles Ducroy and his two companions near the old cabin, how they had followed the men and listened to their conversation.

“Ducroy was trying to get these other chaps to go in with him on some crooked deal, and they were afraid because they said it was too dangerous,” explained Frank. “Ducroy told them they’d make ten thousand dollars apiece out of it. Perhaps that was what he meant. He planned to steal some of the mail bags.”

Fenton Hardy was interested.

“Certainly a suspicious conversation,” he admitted. “Still, the mail bags weren’t worth any thirty thousand dollars, if what the post office people tell me is correct. They were worth about two thousand dollars at the most. Besides, Giles Ducroy is already under suspicion.”

“Has he been arrested?” asked Joe.

Fenton Hardy shook his head.

“When the theft occurred, the authorities first thought of Ducroy, because they knew he had been discharged and was probably looking for a chance of revenge. So their first action was to investigate his movements on the day of the robbery.”

“And what did they find?”

“He wasn’t near Bayport at all. He was in Philadelphia—at least, he has such an alibi.”

“Can he prove it?” asked Frank.

“He had two witnesses to prove it. So nothing could be done against Ducroy.”

“I’d like to know who those witnesses were,” said Frank. “I don’t believe he was in Philadelphia at all.”

The boys were openly dubious about Ducroy’s alibi.

“He’s a slick one, Dad,” declared Joe. “He may look dumb, but he’s not as dumb as he looks.”

The news that Giles Ducroy had a proven alibi to clear himself of suspicion in the affair of the stolen mail sacks disconcerted the Hardy boys for a time.

When their father told them about the robbery their first thought was that Ducroy and his two companions were the guilty parties, for the theft seemed to be linked up in some manner with the conversation the lads had overheard in the cabin at Beach Grove. However, there now remained the fact that Ducroy had an alibi, and also the fact that the mail sacks were by no means worth the amount the former pilot had mentioned to his companions.

“Just the same,” declared Frank that afternoon, “I’m convinced that Ducroy had something to do with the affair, alibi or no alibi.”

“Perhaps the mail sacks weren’t stolen by Ducroy,” suggested Joe. “Perhaps he went to Philadelphia, so he would be able to prove an alibi, and left Newt Pipps and Ollie Jacobs to commit the actual robbery.”

“It could have been worked that way. I’ll tell you what we’ll do, Joe. Let’s take the roadster and drive back down to Beach Grove. I’d like to take another look at that cabin. Perhaps we’ll find a few clues there that may help us.”

Joe was impressed by this suggestion, and in a short time the Hardy boys were speeding down the Shore Road in their car. When they reached the grove they left the roadster and made their way through the woods down the path toward the little cabin.

“We didn’t have the opportunity to look through the place when we were here before,” Frank pointed out. “They may have left something behind, a few notes or plans for instance, that will give us a better idea of what they were talking about.”

“It’s a mighty suspicious thing that a robbery should occur at the airport so soon after Giles Ducroy and his friends were talking about some crooked scheme.”

“That’s the way I feel about it.”

The boys entered the cabin. The door was unlocked and the place was deserted. It was sparsely furnished with only a small wooden table, two broken chairs and a few boxes.

“Nothing much here,” Frank remarked. “Still, it won’t do any harm to look around carefully.”

Joe came upon an empty bottle over in a corner, perhaps the bottle from which the men had been drinking on the afternoon of the picnic. Frank’s attention was attracted by a number of cigarette stubs on the table.

“Sometimes a little thing like a cigarette turns out to be a mighty valuable clue,” he observed, examining the stubs. Most of them were very short, but on one, a trifle longer than the rest, he found the letters “RE.” The rest of the word had been obliterated with the burning of the cigarette.

“I wonder what make of cigarettes they were smoking,” he said. He searched the cabin thoroughly and at last he found what he was looking for. Beneath one of the boxes he saw a crumpled paper package. He picked this up, unfolded it, and examined it carefully.

The package had once held cigarettes, and across the front he saw the name, “Red Ribbon Cigarettes.”

“Not much of a clue there,” laughed Joe. “All gone up in smoke.”

“You never can tell,” returned his brother, pocketing the package.

“Better be careful. If mother finds that package in your pocket she’ll think you’ve been smoking.”

“Mother knows us well enough to know we don’t smoke,” Frank said. “I have a hunch that this little package may come in handy some day.”

Although the boys searched the bare little cabin high and low, they found nothing else that might help them. Their search for clues appeared to have been a failure.

“Ducroy and his friends were too wise to leave any notes that might incriminate them,” Joe said, as they went away. “I guess we’ll have to tackle the case from another angle.”

“Dad’s handling it to the best of his ability, and I guess he will be in a position to get information that we’ll never run across. All we can do is to keep our ears open and, if we hear anything, let him know.”

The boys returned to Bayport, somewhat disappointed; but when they were near their home they dismissed the mail bag mystery from their minds, for they met Chet Morton and Biff Hooper.

“Just who we were looking for!” exclaimed Chet. “We called at the house, but your mother said you had gone out.”

“What’s up?” asked Joe.

“Why, Biff and I thought it would be a fine afternoon to take a little boat trip. I thought we could go down to Cabin Island and see that everything is in shape. We can find out what we need to take down there for our outing. I know we left some kitchen dishes and other things there last winter, but they may be gone by now. We can look the place over and make a list of what we’ll have to bring along.”

“You’re going on the trip, aren’t you?” asked Biff.

“Sure, we’re going. I guess it isn’t too late in the day to go down to the island, Chet. Come on with us and we’ll take the car back to the garage.”

The Hardy boys drove back to the house with the other lads, told their mother that they were going down to Cabin Island in the boat, and started off for the boathouse. The lads did not take any food with them, for the Hardy boys’ motorboat, The Sleuth, was a speedy craft and was quite capable of taking them to Cabin Island and back by evening.

It was a warm, sultry afternoon, and the lads were glad to be out on the cool bay, away from the sweltering heat of the city. It had been an unusually close day, and there had been occasional rumbles of distant thunder.

“We’re going to have a thunderstorm to-night, I’ll bet,” said Biff, as the boat nosed down the bay.

“I don’t think it’ll break before we get back,” said Frank. “It’s a long way off yet.”

The Sleuth drummed along smoothly, and Joe lolled at the wheel. Once they left the narrow end of the bay upon which the city nestled in the glaring sunlight, there was a stiff breeze, vigorous and refreshing.

“Oh, boy!” gloated Chet. “This is the life!”

“It sure is!” the others agreed.

By the time they came within sight of Cabin Island, leaving Bayport far behind, they could see rolling black clouds in the east, and the murmur of thunder had become more continuous.

“We shan’t be able to stay long, I’m afraid,” remarked Frank. “That storm is coming up more quickly than I thought it would.”

“Oh, it’s hours away yet,” scoffed Chet. “You’ll see.”

“Let’s hope so. Anyway, we won’t lose time. We’ll just go up to the cabin and take a quick look around. I don’t want to get caught out in a bad storm. The Sleuth is a good little boat, but the waves run mighty high in the open bay around here.”

Those who followed the adventures of the Hardy boys in “The Mystery of Cabin Island,” are aware that the island, which was owned by Elroy Jefferson, a wealthy antique dealer of Bayport, lay far down Barmet Bay in a little cove. There was a large cabin, built by Mr. Jefferson, fully equipped and furnished, but not occupied by the owner because it had been built for the use of his wife and son. They had died, and the associations of the island had been so painful to him that he had never gone near the place again. However, grateful to the Hardy boys because they had recovered his stolen automobile and because they had solved the mystery of a valuable stamp collection that had been purloined from him, he had turned over the key of the cabin to them with full permission to make use of the place on any of their outings.

They ran the motorboat into the little boathouse and made it secure, then clambered up the familiar path toward the cabin. They had last been on the island in the winter time, when everything was blanketed with snow. Now it was doubly beautiful with its grassy, wooded slopes and its tall trees, among which the cabin stood.

“Make it snappy,” cautioned Frank. “That storm looks worse every minute.”

He opened the cabin door and they stepped inside. The chimney, which had been damaged during a storm the previous winter, had been repaired by some workmen whom Elroy Jefferson had sent to the island, and the place had been thoroughly cleaned. Some new furniture had been installed and on going to the kitchen the boys found a full supply of dishes, kettles, frying pans, cutlery—everything they could possibly need except provisions.

“He must have expected us to come here during the summer!” exclaimed Joe, in delight. “He certainly hasn’t overlooked anything.”

“Mighty good of him, I’ll say!” Chet declared, and his sentiment was echoed by the others. “We have nothing to worry about in the way of kitchen equipment, at any rate. We’ll need only blankets and grub.”

“I think we’ll have a fine outing here.” Frank looked out the window. “Well, we’ve found that we don’t have to worry about the kitchen end of it. Now let’s be going. The storm is right overhead.”

When the boys stepped outside again, all saw that Frank’s desire for haste was well-founded. There were white caps rolling on the bay and the sky was growing black. Even as they started down the path there was a flash of lightning and an ear-splitting crash of thunder. Then followed a gusty shower of rain. The trees were bending before the rising wind.

“We’ll never make it!” shouted Frank. “No use trying to get back to Bayport now.”

“What’ll we do?” asked Chet.

“I guess we’d better go back to the cabin.”

“We haven’t any food, no blankets, no oil in the lights. We’ll probably be stranded here all night.”

“This is a fine lookout,” grumbled Biff. “I wish I hadn’t come.”

As the boys looked out over the bay they could see a sweeping wall of rain approaching above the stormy waters. His companions realized that Frank Hardy was right. They could not hope to brave the perils of that storm by venturing a return to Bayport that night. On the other hand, the prospect of being stranded on the island without food was far from pleasing.

Rain was pouring now. Another lightning flash zigzagged its way through the clouds. Another thunderclap crashed forth.

“Do you think we can reach the village?” shouted Joe.

Frank had almost forgotten about the little village on the mainland not far away which they had visited several times during the winter. Amos Grice, the storekeeper, was a good friend of theirs and his hospitality was preferable to spending a night in a dark cabin, without food or blankets.

“We’ll try it, anyway. If we get into the shelter of the shore I think we can make it all right. Come on fellows!”

The others followed Frank down the steep path to the boathouse, where all clambered into The Sleuth. The engine roared as the boat sped out into the rolling waves, this time Frank taking the wheel.

Smash!

A great wave broke over the bow, drenching the boys to the skin. The full force of the wind caught them as they rounded the point of the island. They were plunging out into a raging waste of waters.

“We’ll never make it!” groaned Chet.

Frank Hardy set his jaw with grim determination as he drove the motorboat into the storm. It was too late to turn back.

The storm had swept up with such speed that Frank realized now that he had underestimated it. The wind was terrific and the waves were high. They battered against the staunch little boat, drenching the boys with flying spray.

Frank headed toward the mainland, but then he saw that he could not hope to find shelter from the wind along the shore. The waves were rolling in and dashing against the rocks. The motorboat would have no chance there. It would be flung hither and thither and battered to pieces.

“Nothing for it but to head right into the wind, I guess,” he shouted, above the howl of the storm.

The other boys were crouching in the bottom of the boat, out of the flying spray. The boat seemed to quiver with successive shocks as it bucked the waves.

The rain was driving into their faces. Through the downpour Frank could not even see the little village toward which they were bound. He wished they had remained on Cabin Island.

The Sleuth, although small, was a strong and well-built craft. The engine throbbed faithfully. None of them dared think of the consequences should the engine fail.

The bow of the craft cut through the rolling waves like a knife. Thunder rolled overhead. The sky was black. The boys could scarcely see the shore. Driving against the wind and the tide, the boat could make little speed, and headway seemed slight.

Nevertheless The Sleuth was edging slowly down the bay, coming ever closer to the little village. Frank peered through the raging storm, hoping to catch sight of the little huddle of houses on the shore.

Lightning flared in the dark sky. Frank held the boat steadily into the wind.

They were all drenched to the skin. Although no one said a word, Frank could see that the others were frightened. As a matter of fact, he was none too confident of the outcome himself.

“It all depends on the engine,” he muttered. “If that fails, we’re done for.”

But the engine had been thoroughly overhauled just the previous week. He was grateful for the foresight that had enabled him and Joe to take this precaution.

Joe crept to the side of his brother.

“Do you think we’ll get there, Frank?” he shouted.

Frank nodded. “It’s dirty weather, but we ought to make it all right.”

Just then he caught sight of the little break in the shoreline that indicated the cove where the village was located. They were still far out, and to reach the village the boat must run diagonal to the waves. This was the hardest test.

The buffeting The Sleuth had previously received was as nothing to what she now suffered. Time and again the boys held their breaths, certain that the boat was about to capsize. Great waves would crash against it, the boat would cant far over on her side, her bow would be buried in the water. Then, like a live thing, The Sleuth would shake herself free, rise above the waves, and go plunging on.

The boys clung to every available hold, fearful of being washed overboard.

Suddenly Joe gave a shout of warning:

“Watch out!”

A great roller was bearing down on them. They ducked, waited——

Crash!

A huge sea of green water engulfed them. For a moment the boat was completely buried beneath the wave. It slipped far over. Frank felt his feet washed from beneath him. He clung to the wheel with all the strength at his command, held his breath through what seemed an eternity of waiting.

Then the motorboat labored free of the wave, slowly righted itself. The water receded. The craft was weighted down by the water that still remained in it, but all the boys were safe. Chet was suffering from a cut across the forehead, where he had been flung against one of the seats; Biff was clutching his wrist, which had been wrenched in his desperate effort to retain his grip on an iron ring; Joe was gasping for breath after his immersion in the water; Frank felt a dull pain in his side, where he had been dashed against the wheel.

More dead than alive, the boys held on. But the village was now in plain view. They had gone through the worst of the storm, and the waves were now hurling the boat in toward the cove.

Frank steered toward a little dock, where the angry waters were dashing themselves angrily against the timbers. He saw a man clad in oilskins running out on the dock, gesturing to them and pointing toward the shore. There was a little boathouse in the cove, and then the man ran from the dock over toward the boathouse, still gesturing.

There was shelter for them. The motorboat would have been dashed to pieces had they tied up to the dock. Frank saw the door of the boathouse open and he drove directly toward it. A great wave caught the craft and it shot forward. A turn of the wheel and he was headed into the narrow opening. He switched off the engine, and then The Sleuth slid gently into the slip.

Tired, exhausted, drenched, the boys clambered out of the boat. The man in oilskins was waiting for them. He seized a rope Frank flung to him and snubbed it around a post.

“Well, now, that was a narrow squeak, if ever I saw one!” he declared in a familiar, nasal voice. “Wust storm we’ve had on this bay for ten years, and you’d be caught in it. You’re mighty lucky, my lads.”

They looked up. They knew that voice well.

“Amos Grice!” exclaimed Frank.

At the sound of his name, the man looked around. Then he recognized the refugees.

“Well, if it ain’t the Hardy boys!” he shouted in welcome. “And Chet and Biff!”

“You certainly did us a good turn that time,” declared Joe.

Amos Grice was soon shaking hands with them, asking a score of questions. How had they come to be out on the bay in the storm? Had they been at Cabin Island? Had they been frightened? How did the boat get half full of water? And so on and so forth. He was a kindly old man, this village storekeeper. He now led the way out of the boathouse.

“Come up to the store,” he said. “Come up and put on some dry clothes. You’re soaked to the hide, all of you. Come up and tell me how it happened.”

“Nothing much to tell, Mr. Grice,” explained Frank. “We were on Cabin Island this afternoon when we saw the storm coming up. We knew there was no chance of getting back to Bayport in time, so we thought we’d run over here, but the storm broke too suddenly for us.”

“It did break sudden,” admitted the storekeeper. “It broke sudden and fierce. I’ve never seen a worse storm in ten years.”

He took them up to the store, and in a warm kitchen at the back he bade them dry themselves by the fire while he hustled about and procured dry clothing. Amos Grice was a bachelor, and while his living quarters were crude, they were neat and comfortable. He was genuinely delighted to see the boys, and he soon busied himself at the stove preparing supper.

After a hearty meal the lads were feeling more comfortable and their hazardous adventure on the bay did not seem quite so perilous as they looked back on it.

“I guess we won’t be able to get back to the city to-night,” said Frank regretfully.

Amos Grice snorted.

“I wouldn’t hear of it!” he declared. “Couldn’t think of it! Just suicide to try it. No, sir, you lads have got to spend the night with me, and glad I am to have you. It’s seldom enough I have company here.”

“As long as you have room for us——”

“Of course I have room for you. There’s two big beds in the spare room, and you’re more than welcome.”

A bell occasionally tinkled out in the store, and Amos Grice bustled away to wait on a customer. However, there were few people in the little village and the night was so wild and stormy that nearly everyone was staying indoors, so the interruptions were few.

They chatted with the old man all that evening, sitting by the fire, and eventually he showed them to a big room where the beds were already made.

“Now,” he said, “sleep as long as you wish and I’ll have some breakfast for you in the morning. No doubt your parents is worryin’ about you, and I’d phone ’em if I could, to let ’em know you’re all safe and sound. But the telephone wires is down somewhere along the line. They’ll likely be fixed by morning.”

“Dad and mother will certainly be worrying about us,” said Joe.

“Can’t be helped,” returned Amos philosophically. “They’ll feel all the better when they know you’re safe.”

The boys were tired and they fell asleep quickly. In the morning when they awakened the sun was shining in the window. The storm was over. Out in the kitchen a fire crackled in the stove and they could hear Amos Grice moving about. There was a savory aroma of bacon and eggs and coffee.

“He’s certainly a good scout!” declared Chet, as they dressed.

“Can’t be beat,” agreed Biff.

When the boys were washed and dressed, they went out into the kitchen.

“Sleep well?” inquired Amos.

“You bet!”

“That’s good. Breakfast is ready. Pull your chairs up to the table and get on the outside of some bacon and eggs. There’s plenty, so don’t be afeared to ask for second helpin’s.”

“Is the telephone working, Mr. Grice?” asked Frank. “I’d like to call them up at home if I can.”

“Yep, the phone is workin’ again,” the storekeeper assured them. “I know, because I was callin’ the operator this morning. Big doin’s in Bayport last night.”

“What was that?” asked Joe, interested.

“Big robbery at the airport. One of them airplanes was robbed of a lot of mail worth more’n twenty thousand dollars, so the telephone operator was tellin’ me.”

The Hardy boys looked at one another in amazement. A second robbery at the airport! Impulsively, Frank exclaimed:

“Ducroy again!”

“What’s that?” demanded the storekeeper abruptly, in response to Frank Hardy’s inadvertent exclamation.

“Nothing,” answered Frank. “I was surprised—that’s all. You see, there was a robbery at the airport only a day or so ago.”

“Another one, eh? Well, they oughta watch that place more careful, that’s all I can say. People won’t be sendin’ their letters by airplane if they think they’re goin’ to be stolen all the time.”

“That’s a case for you fellows,” said Biff.

Neither Biff nor Chet were aware of the depth of the Hardy boy’s interest in the airport robberies.

“Did the operator tell you anything more about that affair, Mr. Grice?” asked Frank, after a pause.

“Nothin’ more than what I’ve told you. She just said there was a big robbery and twenty thousand dollars’ worth of mail had been stolen last night.”

Joe went to the telephone. After some delay he managed to get the Hardy home in Bayport on the wire. His mother’s voice answered.

“Hello, Mother! This is Joe talking.”

Her voice had an unmistakable note of relief as she answered:

“Joe! Oh, I’m so glad to hear your voice again. Your father and I have been greatly worried about you. Where are you? What happened? Why didn’t you come home last night?”

“Don’t worry, Mother. We were caught in the storm and we couldn’t get back. We’re quite safe. We’re at Mr. Grice’s place, down below Cabin Island.”

“Well, I’m glad to hear that. When are you coming home?”

“We’re coming back to-day. Would you mind telephoning to Mrs. Morton and Mrs. Hooper? Tell them that Chet and Biff are with us and that they’re all right too.”

“I’ll do that, Joe. Just a minute. Your father wants to speak to you.”

Joe waited a moment. Then he heard his father’s voice.

“Hello, Son. You’ve given us a pretty bad scare.”

“We’re sorry, Dad, but we got caught in the storm.”

“Let me in on this, Joe,” begged Frank; and when Joe had put the telephone in his brother’s hand the older Hardy boy continued: “Hello, Dad! Worried you and mother, did we? Sorry. But we’re all right. Will tell you about it when we get back.”

“Well, I’m glad you’re all right. Now listen. I want you and Joe to come home at once.”

“Sure. We are just going to leave.”

“Come back to Bayport at once. Something has happened.”

“What’s wrong, Dad?”

“I’ll tell you when you reach here. But don’t lose any time.”

“Is it about the airport robbery?” asked Frank.

“How did you know there was a robbery at the airport?” demanded his father in an anxious tone.

“We heard it this morning through Mr. Grice.”

“Well, it’s connected with the robbery, but it’s a little worse than that. Come right home, mind now.”

“All right, Dad. We’ll leave right away.”

Frank hung up the receiver and turned to the others. He was puzzled.

“I guess we can’t hang around here this morning. Dad wants us back right away. He seems awfully anxious.”

“Anything wrong at home?” asked Joe quickly. “Mother didn’t say so.”

“Everything’s all right there, I guess. But Dad has something on his mind. He said he’d explain it when we got home.”

“Shucks!” grumbled Amos Grice. “And I counted on takin’ you lads out fishin’ this morning.”

“I guess we’ll have to call it off, Mr. Grice. Some other time, perhaps.”

Chet Morton sighed and ate another slice of bacon.

“I guess we’ll all catch it when we get home. Was your Dad sore, Frank?”

“No, he didn’t seem angry. I can’t imagine what’s wrong. Well, I guess we’ll have to bail out the boat right after breakfast and start for home.”

After they had eaten, Amos Grice helped them bail out the motorboat. It had stood the storm well, in spite of the terrific battering it had received. The old storekeeper was disappointed because his young guests could not remain with him longer, and when they thanked him heartily for his kindness he waved their gratitude aside.

“A pleasure,” he told them. “I’m always glad to see you. Any time you’re down this way, be sure and drop in.”

“We’ll pick better weather next time, Mr. Grice,” laughed Chet.

“In fair weather or foul, you’re always welcome.”

They got into the boat and started off. The storekeeper stood on the dock and waved to them as they departed. Then he turned and walked slowly up toward his store.

Joe came up and sat beside Frank, who was at the wheel.

“What do you think has happened, Frank?”

“I can’t imagine. It has something to do with the robbery last night, I’m sure.”

“But why should dad want us back right away?” Joe insisted.

Frank shrugged. “It beats me. Perhaps he has some work for us to do, helping him trace the thieves.”

“Maybe that’s it. I sure hope so.”

Frank was silent for a while. Then he said:

“I wonder if Giles Ducroy and his friends will have an alibi this time.”

“It will have to be a mighty good one. Just think of it! Two mail thefts in a row. Whoever did last night’s job must know the run of the airport pretty well.”

“Whoever committed the first robbery knew the lay of the land too. If we solve the first one we’ve solved them both.”

“We?” said Joe. “I don’t think we’ll have much chance to solve it. This is dad’s case. I’ll bet it won’t take him very long to clear it up, either.”

But, with all their conjectures, the Hardy boys had no suspicion of the real reason for their summons back to Bayport. Had they known what had caused that note of urgency and anxiety in their father’s voice, they would have been dumbfounded. A stunning surprise awaited them.

They passed Cabin Island and headed out of the cove into the open bay. The water was still rough from yesterday’s storm, but there was little wind. After a while the city came in sight far in the distance, shining in the sunlight, beneath a pall of smoke from the factory chimneys.

It was a few minutes before twelve o’clock when the boys finally arrived at Bayport and ran The Sleuth into the boathouse. To their surprise they saw that a man was lounging in the doorway. He was a big man, with a fat, stolid face, and he was chewing at an unlighted cigar, his thumbs in his vest pockets.

“Good mornin’, boys,” he rumbled.

They recognized him as Detective Smuff, of the Bayport police department, a worthy if unintelligent officer. Frank could not imagine why Smuff should be in the boathouse, apparently waiting for them, but he grinned amiably at the detective.

“Hello, Mr. Smuff! It is an unexpected surprise to find you here.”

Smuff nodded portentously. “It is?” he asked.

“Last person in the world we ever thought would come down to welcome us,” declared Chet. “I tell you, Mr. Smuff, we sure appreciate this. It isn’t often we have a reception committee on the job when we come back from a little outing.”

“Well,” said Smuff, “I’m on the job this time.” He turned to the Hardy boys. “I’ve been sent down here to give you a message as soon as you got in,” he informed them.

“A message!” exclaimed Joe. “Who from?”

“The chief. He wants to see you down at headquarters.”

The Hardy boys stared at the detective in amazement.

“The chief? Wants to see us?” ejaculated Frank.

“Yep.”

“What about?” demanded Joe.

Smuff looked very mysterious. “You’ll know all about it when you get there,” he said.

“You’re going to be pinched for staying out all night,” laughed Chet. “That’s a fine thing to do, Smuff—pinch our chums the minute we get back to town. A fine reception committee you are!”

“I didn’t say anybody was pinched,” returned Smuff cautiously.

“Well,” said Frank, “this is a surprise! Won’t you tell us what it’s all about?”

Smuff shook his head. “My orders,” he explained, “was to come down here and wait for you and to tell you to come up and see the chief right away.”

“Why not let us wait until after lunch? We want to go home and eat and change our clothes.”

“Orders is orders,” insisted Smuff firmly. “The chief wants to see you right away.”

“All right,” sighed Joe. “I suppose we’ll have to go. But I wish I knew what it was all about.”

“Me, too,” rejoined his brother.

Biff, who had been tying up the boat, came forward.

“He probably wants to fire Smuff, here, and give you jobs on the detective force,” he suggested, with a grin.

Smuff glowered. “My job is good for a long time yet,” he observed pompously.

“Come on,” said Frank. “There’s no use standing here arguing about it. We’ll go with you, Smuff.”

“I have my car right here at the door,” said the detective.

“That’s service,” chirped Chet. “Biff and I will run along home. Our parents will be worrying themselves sick if we don’t show up. So long, fellows! If Smuff claps you into a cell, we’ll come and bail you out!”

Chet and Biff hastened off down the street while the Hardy boys clambered into Smuff’s car. The detective wedged himself in behind the wheel and they drove the few short blocks to police headquarters.

Here they were ushered into the private office of Chief Collig himself, a fussy little man with a vast sense of dignity. The chief was sitting at a huge desk, scanning a large number of photographs of criminals, but he stacked these to one side as Detective Smuff brought the boys in.

“Good day, Chief,” said Frank easily. “Detective Smuff, here, said you wanted to see us.”

“I did,” snapped Chief Collig.

“Well, here we are.”

“You’re wanted,” said Collig briefly.

“Wanted?” asked Frank. “What do you mean?”

“You’re wanted by the postal authorities. I have orders to place you under arrest.”

The lads were so astonished that they could scarcely speak. Under arrest? This was the last thing either had expected.

“What for?” gasped Joe. “What’s the idea?”

“You know about the airport robbery, don’t you?” demanded Chief Collig.

“Yes, we know about it. But——”

“Well, they say you did it. I have orders to arrest you both.”

The Hardy boys were absolutely dumbfounded. The charge of theft seemed so absurd that they were at first tempted to laugh. But they saw that Chief Collig was in deadly earnest. His face was serious and his eyes regarded them sternly.

“The postal people have evidence against you lads,” he said. “A mail sack with about twenty thousand dollars’ worth of mail was stolen. They took out a warrant against you this morning.”

“Why, this is the craziest thing I ever heard of!” declared Frank hotly. “Us? Mixed up in that mail robbery? Why, we weren’t even near Bayport when it happened.”

“How do you know so much about when it happened?” asked the chief quickly.

“We were away down the bay all last night and we heard it over the telephone this morning.”

“Pretty good alibi,” said the chief. “And what time do you think the robbery occurred?”

“Last night.”

“Well, it didn’t happen last night. It happened yesterday afternoon, early. And you boys didn’t leave here in your motorboat until late in the afternoon. The robbery wasn’t discovered until last night. Where were you yesterday afternoon?”

“Why, we went in our roadster down to—” began Joe, but a warning kick from Frank silenced him. It would not do to tell Chief Collig that they had been in Beach Grove, seeking clues against Ducroy and his friends in the deserted cabin.

“Where did you go in your roadster?” asked Chief Collig.

“We went for a drive,” admitted Joe lamely.

“Where to?”

“Well,” said Joe, “we went down the Shore Road.”

“To the airport?”

“No.”

The chief pursed his lips. “You parked your car in Beach Grove,” he said. “I have a witness to prove it. And from there you walked through the bush to the airport.”

“We didn’t!” snapped Frank.

“Where did you go, then?”

“We just took a walk through the grove.”

“Can you prove it?” asked the chief.

“You’ll have to take our word for it, that’s all I can say.”

The chief shook his head. “I can’t take your word for it,” he returned. “The evidence against you is too strong.”

“Are you going to lock us up?” Frank asked.

“You’re under arrest. That’s my duty.”

“Won’t you let us go home first? We’d like to talk this over with our father.”

“He knows about it,” said Collig.

“But we want to see him, anyway. You come with us, Chief. We won’t try to run away.”

The chief considered this for a moment. “I guess there ain’t any harm in that,” he decided finally. He got up, put on his uniform cap, and led the way out of the office.

A department automobile was waiting at the curb and Chief Collig ordered the chauffeur to drive to the Hardy home on High Street.

“What makes you think we’re mixed up in this business?” Joe inquired. “Is it just because we were out on the Shore Road yesterday?”

The chief shook his head. “We didn’t know that until later,” he said. “After we began checking up on you two lads we found that you had been on the Shore Road.”

Frank was surprised.

“What made you check up on us? Why should you suspect us? We have never been in trouble before.”

“I know that,” returned Chief Collig. “You would never have been suspected hadn’t it been for the clues.”

“Clues?”

“There were clues found after the robbery. I think you’ll have a hard time explaining them.”

Beyond that, Chief Collig would volunteer no further information. The boys were puzzled and apprehensive. The chief’s mysterious reference to clues made their position seem more serious than they had at first imagined. Conscious though they were of their own innocence, they realized that their visit to Beach Grove made it almost impossible for them to prove an alibi and they readily saw that they might find themselves in a bad plight.

At the Hardy home they found Fenton Hardy awaiting them. Mrs. Hardy seemed anxious and frightened, particularly when she saw Chief Collig, but her husband managed to allay her fears.

“It’s all a bad mistake, Laura,” he assured her. “The boys have done nothing wrong. We’ll go into the matter thoroughly and see where the trouble lies.”

He ushered Chief Collig and his sons into the study, then closed the door.

“Well, Chief,” said the great detective easily, “this seems to be a bad mix-up. I didn’t meet the boys when they arrived this morning because I knew you wanted to have a talk with them and I didn’t wish to interfere. How do things stand now?”

“They’re under arrest,” returned Collig. “They wanted me to bring them home so they could see you, and I consented.”

“Under arrest, are they? Well, that’s bad. I thought they would be able to prove an alibi.”

“They can’t,” said the chief. “It isn’t my doing, Mr. Hardy. The post office people took out this warrant and if I didn’t arrest them, somebody else would.”

“I quite understand that, Chief.” Mr. Hardy turned to his sons. “Well, boys, this looks pretty bad. What have you to say?”

“It’s a big surprise to us, Dad,” said Frank. “The first we heard of the robbery was over the telephone this morning. We don’t know anything more about it than that. I think you know well enough that we’re innocent.”

Mr. Hardy nodded. “I’m quite sure of that. The fact is, however, that there is some damaging evidence against you. It will have to be explained. When were you at the airport last?”

“We’ve never been at the airport, Dad.”

“You’ve never been there at any time?”

“No,” said Frank. “We started out to visit the airport one day, but that was the time Giles Ducroy’s plane crashed when we were still some distance away. We turned back and returned to town.”

“Where were you yesterday afternoon?”

“We took the car and went for a drive out the Shore Road, to Beach Grove.”

“Did anyone see you? Can anyone prove it?” inquired Mr. Hardy, eagerly.

Frank shook his head. “No one saw us, so far as I know. You’ll just have to take our word for it.”

“That’s quite enough for me,” admitted Mr. Hardy. “But the police require something more substantial than that.”

“What’s all this about clues?” demanded Joe. “Chief Collig says they found some clues at the airport that seemed to connect us with the robbery. What were they?”

“We found a sweater, for one thing,” declared Chief Collig. “It was a blue sweater, with white trimmings.”

“I had a blue sweater with white trimmings,” said Frank promptly.

“Where is it now?” asked the chief.

“I lost it.”

Chief Collig nodded grimly. “You lost it at the airport. That’s where it was found.”

“My sweater? Found at the airport?” exclaimed Frank, dumbfounded.

“There are plenty of blue sweaters like Frank’s,” scoffed Joe. “How do you know it was his?”

“Because,” returned the chief, “his name was in it. It was on a tag inside the collar.”

Frank was silent for a moment. He realized how damaging the discovery of the sweater might be.

“I did have a tag with my name on it, stitched inside the collar of my sweater,” he admitted. “I guess it must be mine, all right. But I didn’t leave it there. I lost the sweater more than a week ago. I left it out in the barn one night and I haven’t seen it since.”

“Well,” said Chief Collig, “the sweater has been found. It was lying in the airport, in a place where you—where the thieves lay in hiding until the mail bags were left unguarded.”

“Anyone could have put the sweater there,” declared Mr. Hardy. “The person who took Frank’s sweater from the barn could have done that.”

“We have more evidence than that,” insisted the chief. He turned to Joe. “Let me see the soles of your shoes?”

Mystified, Joe elevated his feet. The chief looked at the soles, then referred to a paper which he removed from his pocket.

“You’ll find it hard to explain that,” he said, and placed the paper on Fenton Hardy’s desk.

Joe’s shoes had been bought at an exclusive sporting goods store in Bayport just a few days previously. They were new, and of an original design, the rubber soles were stamped in a peculiar manner. Probably no more than a few pairs had been sold since the shipment arrived.

The paper which Chief Collig produced had a penciled drawing which corresponded to the stamped design on the soles of Joe’s shoes.

“That drawing,” explained the chief, “was made from the footprints found at the scene of the robbery. What size of shoe do you wear?”

“Size six,” returned Joe.

“These footprints were made by a size six shoe. I went to the shoe dealers in town and I found that only one merchant handles shoes of that type. He says they are a new kind of shoe and that he has sold only one pair of sixes since they arrived. And he sold that pair to you. How do you explain that?”

“I didn’t leave the footprints there,” insisted Joe doggedly. “Someone else must have a pair of those shoes, same size as mine.”

“You are wearing the only pair of those shoes ever sold in Bayport,” declared Chief Collig. “The footprints were found at the airport in the mud. And there’s something else.” He took an object from his pocket and held it out in the palm of his hand. “Do you recognize that?”

“My knife!” exclaimed Frank.

“You admit it, eh?” The chief grunted with satisfaction. “You see the initials on it. J. H. to F. H.?”

“Joe gave it to me for Christmas, and he had the initials engraved on it.”

“I suppose,” sneered the chief, “you lost the knife at the same time you lost your sweater?”

“To tell the truth, I did.”

Fenton Hardy was pale and distressed.

“This looks very bad,” he said to his sons. “Have you any idea how the sweater and the knife came to be there, Frank?”

“None at all, Dad, unless the person who stole them from me left them at the airport.”

“And you, Joe? How about the footprints?”

“All I can say is that somebody else must have a pair of shoes like mine. Neither Frank nor I ever went near the airport.”

“I think,” said Fenton Hardy, “it wouldn’t be a bad idea if we went out to the airport now. We’ll have to look over the ground.”

Chief Collig accompanied Fenton Hardy and the two boys out to the airport, taking them there in his own car. The road entering the grounds was under guard, and the big hangars were closely watched, the authorities evidently taking no chances on a repetition of the robbery. However, Chief Collig was readily admitted and the party proceeded to a hangar where a newspaper photographer was busy taking pictures.

“I’d like to see those footprints, Chief, if you don’t mind,” said Mr. Hardy.

“They haven’t been touched,” said Chief Collig. “I gave strict orders they weren’t to be disturbed.”

Close by the hangar wall a few boards covered the ground. The chief raised them, and in the ground beneath they could see the clear imprint of a foot. The marks of the rubber sole were identical with those made by Joe’s shoes.

“Let’s see how your foot fits that,” suggested the chief, turning to Joe.

Without hesitation, Joe stepped forward. He placed his right foot in the print. It fitted exactly. When he removed his foot there had been not the slightest change in the original print in the ground.

“Yet you said you were never here before!” exclaimed the chief.

“I still say it,” Joe insisted.

“Then how do you account for that footprint? Same size, same marks, same everything.”

“Somebody must have had a shoe just like mine. That’s all I can say.”

The chief sniffed dubiously. Then Fenton Hardy, who had been examining the footprint, made a suggestion.

“Joe,” he said, “I want you to stand in the earth right beside that other footprint. Just walk across there, stand for a moment, and move away.”

Wondering, Joe obeyed. When he had done as his father asked, there were several new footprints in the soft earth. Mr. Hardy looked at them closely.

“What do you think of that, Chief?” he asked.

Chief Collig looked down at the footprints.

“Not much difference, so far as I can see,” he grunted.

“Not much. But there is a difference, isn’t there?”

“The footprints Joe just made don’t seem as heavy as the other one,” admitted the chief.

“They certainly aren’t. You can see how light the impressions are in the earth. That first footprint is pressed down quite heavily. You couldn’t help but see it, and I think it was meant to be seen. Joe’s natural footprints, on the other hand, are scarcely visible.”

“What of it?” demanded the chief.

“I mean,” said Fenton Hardy, “that the footprint you found here is not Joe’s natural footprint at all. It’s all very well to say that the size and the sole markings are identical, but there is more to a footprint than that. The first footprint was made by a very heavy person, as you can see by comparing it with the footprints Joe made just now.” He turned to his son. “How much do you weigh, Joe?”

“One hundred and twenty-five pounds,” Joe answered promptly.

“That’s not very heavy. But that first footprint was certainly made by a person weighing considerably more than that. The earth here is no harder now than it was at the time of the robbery, because it has been covered over by the boards, so I think the test proves itself. Then, to go further, wasn’t there another footprint, Chief? You have shown us only one, the conclusion being that the thief was a one-legged man.”

“There’s another footprint,” declared Collig. “Here it is.” He pointed to an impression in the earth a short distance away.

Fenton Hardy took a small folding measuring rule from his pocket and measured the distance between the two original prints. Then he measured Joe’s footprints.

“More proof,” he said finally. “The distance between these first two prints is a good seven inches more than the distance between Joe’s actual footprints. That proves that the man who wore those shoes was a good deal taller than Joe, with a longer stride. It also proves that when he made that heavy print in the mud he was not simply standing still, which might have caused the print to be heavier by reason of his weight. Otherwise his feet would have been close together. He was walking, just as Joe was walking a moment ago.”

Chief Collig was puzzled. Fenton Hardy’s deductions came as a rude shock, for the chief had already made up his mind that the Hardy boys were guilty and the evidence had seemed conclusive to him. He was not a man who admitted a mistake readily and he clung obstinately to his original belief.

“I don’t care how you figure it out,” he said roughly. “Your boys can’t explain how that sweater and the knife got here. And they can’t prove an alibi. I’m not going to let them go just because one footprint is a little bit heavier than the other.”

“You mean we’re still under arrest?” asked Frank anxiously.

The chief nodded. “You’re under arrest,” he said. “We’d better be starting back to the city.”

Fenton Hardy patted Frank’s shoulder.

“Never mind, Son,” he said. “I’m afraid I can’t convince Chief Collig just now, but at any rate I’m sure of your innocence. And we’ll prove it yet.”

There was nothing more the detective could do. They left the airport and got back into the chief’s car. Gloomily, they drove back to the city.

That afternoon, Frank and Joe Hardy were arraigned before a magistrate and, after the evidence had been presented, they were held for trial on the serious charge of robbing the air mail.

“Held for the robbery!” cried Joe, aghast.

“It’s the most ridiculous thing I ever heard of,” declared his brother. “What would we rob the mail for?”

“Gee, Frank, this will give us a black eye all right.”

“Don’t I know it? But I don’t think our real friends will believe a word of it.”

“Just wait till the newspapers come out. They won’t do a thing but spill it all over the front page!”

“That’s the worst of it. It will make mother feel pretty bad.”

“Yes, and when Aunt Gertrude hears of it she’ll say ‘I told you so.’ ”

“It’s a blamed shame, that’s what it is. I’d like to get back at the Chief for this.”

“So would I.”

This development caused a sensation in Bayport. When the afternoon papers came out with headlines, “Noted Detective’s Sons Held For Air Mail Theft,” friends of the boys and of Fenton Hardy could scarcely believe the news. On every hand people said, “There must be some mistake. The Hardy boys would never do a thing like that.” Scarcely anyone outside the police department could be found who actually believed the lads were guilty.

Nevertheless, this did not make the situation any easier for Frank and Joe Hardy. They were in jail, and the prospect of release seemed remote, because bail had been set in the heavy sum of fifty thousand dollars.

Fenton Hardy was not at all rich, and although he would have placed his entire fortune at the disposal of his sons, he was finding it difficult, if not impossible, to raise the big sum required for bail. He called on the boys late that afternoon and visited them in their cell, ruefully confessing that he had been unable to raise the money.

“I’m sorry, boys,” he said. “I hate to see you stay here in jail, particularly when I’m sure you’re innocent. But you won’t be here long. I’ll do my best to borrow the money to-morrow.”

“Don’t worry about us, Dad,” urged Frank. “Fifty thousand dollars is a lot of money.”

“Mighty slim evidence they’re holding us on,” complained Joe. “If they would only bring us to trial right away, we’d be acquitted sure.”

Just then they heard a disturbance in the corridor. Two men were arguing with one of the guards.

“But I tell you, we must see them right away!” demanded a familiar voice. “It’s an outrage! A scandal!”

“You’ve got to have a permit from the chief,” expostulated the guard.

“Permit! Bah! Here’s your permit! Now can we get past?”

“Hurd Applegate!” exclaimed Frank, in astonishment.

Two elderly men came hastening down the corridor toward the cell, a guard following close behind. One of them was indeed Hurd Applegate, the wealthy and eccentric man whose family treasure had been recovered by the Hardy boys, as related in the first volume of this series; “The Tower Treasure.” The other man was none other than Elroy Jefferson, the owner of Cabin Island.

“This,” declared Elroy Jefferson, standing in front of the cell and brandishing a newspaper, “is a shame! Nothing less than a shame!”

“A scandal!” fumed Hurd Applegate.

“A shame and a scandal!”

“You’re right, Elroy!” declared Mr. Applegate. “It is a shame and a scandal. I never heard of anything so disgraceful. The Hardy boys in jail! Impossible! And bail set at fifty thousand dollars! An outrage!”

“Idiotic!” raged Mr. Jefferson. He bowed to Mr. Hardy. “How do you do, Mr. Hardy. Mr. Applegate and I were just talking about our stamp collections when the boy came with the afternoon paper. We read it. We saw the headlines. ‘Hardy Boys in Jail.’ And at once I said: ‘This is an outrage!’ ”

“You did, Elroy,” affirmed Hurd Applegate. “And I said: ‘This is a scandal.’ ”

“Yes, Hurd, you said it was a scandal. And it is a scandal. So we put on our hats and came down here immediately.”

“It’s mighty good of you to visit us. You are—” began Frank, when Elroy Jefferson interrupted him impatiently.

“Good of us to visit you!” he stormed. “Do you think we came down here just to visit you? Do you think we’re going to let the Hardy boys stay in jail? Are we going to let them stay in jail, Hurd?”

“We are not!” said Mr. Applegate firmly.

Elroy Jefferson drew two slips of paper from his pocket.

“When we read in the paper that bail had been set in the outrageous amount of fifty thousand dollars, what did I do, Hurd?”

“You wrote a check,” said Mr. Applegate.

“I wrote a check. For twenty-five thousand dollars. And what did you do, Hurd?”

“I wrote one too. I insisted on it.”

“You insisted on it. You wouldn’t let me go bail for the boys myself. The sentiment does you credit, Hurd, but I would gladly have gone bail for the full amount.”

Frank and Joe sprang to their feet.

“We can’t let you do that!” exclaimed Frank. “That is awfully good of you——”

“Good of us!” snorted Mr. Jefferson. “Do you hear that, Hurd? They say it’s good of us. After what they’ve done for us!”

“It’s a pleasure,” declared Hurd Applegate.

“And now,” concluded Mr. Jefferson grandly, “if you will come with us we’ll go upstairs and turn over these checks as bail. The idea! The Hardy boys in jail! Most senseless thing I ever heard of! Why didn’t you call me up on the telephone? I would have been down here inside five minutes.”

“Me too,” chimed in Hurd Applegate. “I would have made it in three minutes, because I live closer.”

“Come along,” said Elroy Jefferson. “Let’s all get out of here.”

The two old gentlemen, fuming, led the way down the corridor, Elroy Jefferson waving the two checks that were to gain the Hardy boys their release.

Thanks to the generosity of Elroy Jefferson and Hurd Applegate, the Hardy boys were quickly released on bail. The two old stamp collectors scoffed when the lads sought to thank them.

“We’re not giving away fifty thousand dollars,” declared Hurd Applegate. “We know you won’t run away. And we know that when your case comes to trial you’ll be able to prove your innocence. So why should we let you stay in jail when you don’t deserve it?”

“Especially after what you did for us in the past,” said Mr. Jefferson. “We’re glad we can return the favor.”

That night, at home, the boys discussed the case with their father. Owing to the arrest of his sons, Fenton Hardy had been told by the authorities that his services in the airport mystery would no longer be required. This was a bitter blow, although he realized that the officials were justified in their action. But he resolved to continue the investigation on his own account.

“I’ll do all I can to clear you,” he promised. “And you must do all you can to clear yourselves. As it stands, they haven’t a very strong case against you, but it’s strong enough to be unpleasant. Our big chance lies in capturing the real robbers.”

“I’m sure that evidence was planted by Giles Ducroy,” declared Frank.

“Just wait until I get my hands on that skunk!” added Joe.

“I’m afraid you won’t lay your hands on him very easily,” said their father. “I wanted to have a few words with him myself, but he seems to have disappeared.”

“Disappeared!” exclaimed Frank, in surprise.

Mr. Hardy nodded assent. “He hasn’t been seen around Bayport for several days.”

“How about Newt Pipps and Ollie Jacobs?” asked Frank. “Are they still in town?”

Fenton Hardy seemed somewhat surprised at mention of these two names.

“Is that who Ducroy has been hanging around with?” he asked. “A bad gang! No, now that you mention it, Pipps and Jacobs have cleared out too. They haven’t been seen in Bayport for more than a week.”

“That looks bad,” said Joe. “If they weren’t up to something queer they wouldn’t have cleared out.”

“I’ll tell you where you may be able to find that pair,” said Mr. Hardy. “Do you know the Raven Roadhouse out on the Claymore Road?”

“I’ve heard of the place,” admitted Frank. “It’s supposed to be a mighty tough hangout, isn’t it?”

“Bad enough. Well, I’ve been checking up on Ollie Jacobs and Newt Pipps and I’ve learned that they make that place their headquarters. If you make inquiries there you may be able to find something about them.”

“We’ll make the inquiries, all right!” declared Frank. “I’m sure they know something about this business. What do you say, Joe? Let’s go out there right now and see what we can learn.”

“I’m with you.”

“Better be careful,” advised Fenton Hardy. “This roadhouse is a tough place and Jacobs and Pipps will likely have some friends there, so don’t give yourselves away.”

“We’ll watch our step,” promised Frank. “Don’t worry. We’ve got to clear up those mail robberies to clear ourselves, and I think the quickest way to go about it is to follow up the Ducroy gang. If they’re not mixed up in it from the start I’m a mighty bad guesser.”

The Hardy boys lost no time preparing for their journey out to the Raven Roadhouse, which was located some five miles from Bayport. Within half an hour they had said good-bye to their parents and had clambered into their roadster.

They drove down High Street, on through the business section of Bayport, and out to the highway. Frank was at the wheel.

“It was certainly mighty white of Mr. Jefferson and Mr. Applegate to go bail for us,” he said.

“They’re real friends,” Joe agreed. “The least we can do now is to clear up this business and show them that their confidence in us wasn’t misplaced.”

“We’ll do the best we can, although it doesn’t look very easy right now. That gang didn’t miss any bets in planting the evidence against us.”

“All the more reason why we should get them, and get them right. After what we heard in the cabin, I don’t think there’s much doubt that Ducroy and his crowd had something to do with the robberies.”

“Well,” said Frank, “we’ll go easy, and with any luck we ought to get some clues that we can follow up.”

They thought they would get to the roadhouse quickly, but a quarter of a mile on came to a detour sign. The road ahead was closed for repair.

“Just our luck,” grumbled Frank. “I know this road was open yesterday.”

“We’ve got to go around the old Rundle farm,” answered his younger brother. “That’s a dirt road, too, all the way.”

“Hope it isn’t muddy. It used to have some pretty bad mud holes in it when it rained.”

Fortunately for the Hardy boys, the detour road proved dry. The worst of the holes had been filled with cracked stone, so they got through without much difficulty.

In due time the Hardy boys approached the Raven Roadhouse. It was a long, rambling building, set back some distance from the road and approached by a winding driveway.

“I guess the best plan is simply to go in and ask about them,” said Frank.

He drove up to the front of the roadhouse. There were no guests present at this hour of the day. A fat man was lounging indolently against a veranda pillar.

The boys got out of the car.

“Too early,” grunted the fat man. “The fun doesn’t start here until after dark.”

“We’re not guests,” returned Frank. “We’re looking for somebody.”

A guarded expression crossed the fat man’s face.

“Who?” he asked abruptly.

Frank looked at Joe. “I don’t know whether we should tell him or not.”

Joe, taking his cue, looked dubious. “We weren’t supposed to tell. Still, it mightn’t do any harm.”

Frank looked around mysteriously. Then he lowered his voice:

“Have you seen Newt or Ollie around lately?”

The fat man regarded him shrewdly.

“Why do you want to know?”

“We have a message for him.”

“Who from?”

Frank shrugged. “Why should we tell you?”

The fat man was silent. Then he said:

“Is it from Sam?”

“Maybe. I’m not talking.”

The fat man seemed impressed.

“Well, you know how to keep your mouth shut anyway,” he said. “And that’s more than lots of people know. I guess you’re regular, all right. Well, I can put you in touch with Ollie Jacobs.”

“How about Newt?”

“He’s not here. I don’t know where he is right now.”

“Where is Ollie, then?”

“Down the road. You know where Greenfield village is, eh?”

Frank nodded. “About two miles farther down the road.”

“Well, that’s where you’ll find Ollie. He’s at the hotel. The clerk will find him for you.”

“Thanks. We’ll go on to Greenfield, then.”

“If you’d like to wait here,” suggested the fat man, “Ollie should be back in an hour or so.”

The Hardy boys had no desire to wait. They were on the trail of the elusive Ollie Jacobs and it did not suit their purpose to meet him face to face at the Raven Roadhouse. They thanked the fat man, got back into the car and drove away.

Within a few minutes they reached Greenfield. It was a meagre little village with a few unprosperous-looking stores and a ramshackle hotel.

“We’ll have to go easy here,” said Frank. “It won’t do to have Ollie Jacobs see us.”

“What should we do? Wait out in front of the hotel?”

“He would probably see us first. No, I think it would be better to go inside and take a look around. Once we locate him we can keep out of sight and then follow him later.”

They parked the roadster in front of the hotel and went inside. The Clerk, a seedy little man with shifty eyes, regarded them with suspicion. By way of explaining their presence, the Hardy boys bought some newspapers and a few chocolate bars, then sat down in the lounging chairs in the main office.

“We’ll just sit tight for a while,” whispered Frank. “If Ollie Jacobs is in the hotel, he’ll probably pass through here on his way out.”

The words were no sooner out of his mouth than Joe gave his brother a sharp nudge and hastily began to unfold one of the newspapers. Frank glanced up. Coming down the stairs was Ollie Jacobs.

The man did not see the boys, or at least did not recognize them, for Frank quickly lowered his head, then he, too, spread out a newspaper so that it concealed him from view. Thus, to the man descending the stairway, the two lads appeared intent on the papers, and their faces were completely hidden.

Another man was coming down the stairs a few steps behind Ollie Jacobs. When the pair reached the office, instead of going toward the door, they sauntered over and sat down a few feet from the Hardy boys.

Frank and Joe were trembling with excitement. Behind the newspapers they were safe from observation.

“I won’t go a cent over eight thousand, and that’s final,” they heard Ollie Jacobs saying.

“We’ll split the difference,” returned the other man, in a wheedling tone. “Make it nine thousand dollars cash.”

“Nothing doing! I’ll give you eight thousand dollars. Take it or leave it.”

“An airplane for eight thousand dollars!” exclaimed the other. “I can’t do it. I’d be losing money.”

Ollie Jacobs laughed. “Even at eight thousand, you’ll be making a good profit.”

“Eighty-five hundred,” pleaded the bargainer.

“I’ve made my offer and I won’t raise it a nickel. I’ll give you eight thousand dollars in cash the moment the airplane is turned over to us. You have the machine within five miles of here, you say. Well, I can have the money within half an hour and we’ll close the deal. So make up your mind, for I can’t be wasting time. If I can’t buy your airplane I can easily find another one.”

Ollie Jacobs got up from his chair. The other man rose quickly and seized him by the arm.

“All right. All right,” he said hastily. “It’s just downright robbery, but I’ll sell you the plane for eight thousand. I won’t be making a cent.”

“That’s your lookout,” returned Jacobs coolly. “You don’t have to sell it.”

“I’ll have the plane ready for you at my farm. As soon as you turn over the money, the machine is yours.”

“The money will be in your hands within half an hour. Are you going to the farm now?” said Jacobs.

“I’ll go there right away and get the plane in shape.”

“Be sure you have the tanks full of gas. I want everything to be in perfect running order. That’s the only condition of sale. I want the plane to be in readiness.”

“You can step right in it and start flying the minute you buy it,” insisted the other man. “And you’re getting a bargain, let me tell you. There isn’t a better machine on the market. If you bought that plane from the factory it would cost you fifteen or twenty thousand dollars.”

“A new plane would cost that much. Yours isn’t worth five. It’s an old crate, almost falling to pieces. You’ve been flying it for more than four years now. Well, the deal is made. You go to the farm and get the machine ready. I’ll be over to take possession in half an hour.”

The two men went out the door and descended the steps. Apparently Ollie Jacobs did not notice the roadster belonging to the Hardy boys, for, after halting for a moment on the sidewalk, he strode briskly down the street in a direction opposite to that taken by his companion.

Frank lowered his newspaper and looked at Joe.

“What do you make of that?” he demanded.

“Ollie Jacobs buying an airplane! That fellow never had eight thousand dollars of his own in all his life.”

“He seems to have it now,” said Frank. “There’s something in the wind.”

“I think we’d better follow him.”

They sprang to their feet.

“There’s no time to lose,” Frank agreed. “I’d like to know what Ollie Jacobs is planning to do with that plane!”

When the Hardy boys left the hotel they saw Ollie Jacobs about a block away, walking quickly down the street toward the outskirts of the village. As unobtrusively as possible, they followed him. They soon found that there was little need for caution, as Ollie Jacobs evidently had no suspicion that he was observed, and not once did he look back.

Leaving the sidewalk, their quarry struck out along a country road in the direction of an abandoned house. Here, instead of passing by, he vaulted the fence, crossed the unkempt yard, and disappeared into the building.

“We’ll have to go carefully,” said Frank. “I’ll bet he’s meeting the others there.”

“That’s where he intends to get the eight thousand dollars, I suppose.”

“Chances are, they’re watching. We’d better go around by the back way.”

At the end of the street, therefore, the Hardy boys did not follow the road, but instead made a detour through the fields, coming around at the rear of the old house. There they made their way carefully across the yard. They knew that they risked detection in so doing, but they were obliged to take this chance.

Luck was with them. They crossed the yard in safety, evidently unobserved by anyone in the house.

They crouched beneath a window and listened. From inside the house they could hear human voices. Frank raised himself slightly and peeped through the window. The room was empty. The voices seemed to be from the front of the house.

He gestured to Joe, and silently they crept on to the next window. Here they had better luck. The window was partly open and they could clearly hear the voices of the men in the room beyond.

The first voice they heard was that of Ollie Jacobs.

“Well,” he was saying, “I guess we can each chip in and make up that money. The plane is waiting for us.”

A familiar voice answered:

“Eight thousand dollars is a lot of dough. But it will be worth it in the long run.”

Frank and Joe exchanged glances. They recognized the voice. Giles Ducroy!

“Are you sure the plane is all right?” demanded the third man—Newt Pipps.

“It’s old, but it’s plenty good enough for our purpose,” returned Jacobs. “She’ll hold four or five men.”

“I don’t want to go flying in some old rattletrap that’ll bust all to pieces in mid-air and kill us all,” demurred Newt.

“Don’t worry. I’ll be in charge of the plane,” declared Ducroy. “I could fly a baby carriage if it had wings. Your precious neck is safe enough.”

“Well, here’s twenty-five hundred dollars,” said Jacobs. “That’s my share.”

“And here’s mine,” said Newt.

“And I’ll make up the other three thousand,” said Ducroy. “You never spent money any better. If this pans out all right it will bring us fifty thousand dollars at least.”

“You say it’s the twenty-eighth or twenty-ninth?” asked Ollie Jacobs.

“Yes,” answered Ducroy. “Pay day is on the first of the month, and they always send the money a day or two ahead.”

“It’ll be a big haul if we get away with it,” declared Newt Pipps. “But it’s certainly risky.”

“You’ve got to take chances to make big money,” Ducroy answered. “Fifty thousand dollars isn’t to be sneezed at.”

“I’m satisfied,” said Ollie Jacobs. “I think we can get away with it. Fifty thousand dollars looks mighty good to me. I think we ought to go right over to the farm, buy this plane, and start out.”

“Where do we go first?” asked Newt.

“There’s an airport about thirty miles from here,” Ducroy said. “It’s just a small flying field—the Riverside Field, they call it. We can take the plane there and wait until everything is ready.”

“What if we’re caught?” asked Newt. “The police in Bayport are on the lookout for us, you know that. If they find out where we are, it will ruin everything.”

“We have the plane, haven’t we? If they find out where we are, we’ll simply fly somewhere else, and dodge them. I have everything all figured out. We’ll be quite safe.”

“Then let’s get going,” said Ollie Jacobs impatiently. “We’re just wasting time by arguing here.”

There was a scuffling of feet, then the slam of a door. After a few moments the Hardy boys peeped around the side of the house and saw the three men going down the road in the direction of the village.

“It looks as if we’ve stumbled on something,” said Joe.

“I wonder what they’re going to do with that airplane. One thing is certain—there’s something in the wind for the twenty-eighth or twenty-ninth of this month.”

“What date is this?”

“The twenty-sixth.” Frank watched the receding figures of the men. “I suppose we ought to follow them.”

Joe demurred.

“Why should we? There’s no chance of losing them now. We know the name of the airport they’re bound for, and we can go there in the car and wait for them.”

“That’s right. We’ll go on to Riverside Field and keep an eye on them from there. But first of all, I think we ought to call up dad and let him know what we’ve learned.”

Joe agreed that this was a sound suggestion. The boys waited until the trio were out of sight, then hastened on toward the village. Their first concern was a telephone, and as they did not want to go to the hotel, in case some of Ollie Jacobs’ friends might be within earshot, they lost some time seeking the telephone exchange, which they finally located in the rear of the post office.

There they put through a call to their father in Bayport. After a wait of about ten minutes, the call was answered. The operator turned to them.

“Mr. Hardy is not at home. Will anyone else do?”

“Anyone at that number,” assented Frank.

He picked up the receiver and heard his mother’s voice.

“Hello, Mother. This is Frank calling.”

“Yes, Frank. Where are you?”

“We’re at a little village just outside the city. Where is Dad?”

“He left for New York an hour ago,” answered Mrs. Hardy. “He just received a telegram calling him to New York on special business.”

Frank was disappointed.

“That’s tough luck. We had some news for him. Well, we’ll just have to carry on alone. If we’re not home to-night, don’t worry about us. We’ve picked up some information that may clear up all this fix we’re in.”

“Don’t stay away too long, Frank,” said Mrs. Hardy. “The police were making inquiries a little while ago.”

“The police? Why?”

“They think you may have run away. They’re afraid you have jumped bail.”

This news came as a stunning shock to Frank.

“Why, that’s nonsense!” he exclaimed hotly. “We’ll be back as soon as we can, and if they make any more inquiries you can tell them so. And when we do come back, they won’t have any further excuse for holding us, for we’ll have the real mail robbers with us.”

“I hope you are right, Frank. If your father comes back, I’ll tell him you called.”

“All right, Mother. And don’t worry about us. We’ll be back home as soon as we can get away.”

Frank hung up the receiver and paid the cost of the call. When he turned toward Joe, however, he found his brother standing in the door, gazing up at the sky.

“They’re away already!” exclaimed Joe excitedly. “Look!”

Frank ran to the door. Joe was pointing up at the clouds. High above them soared an airplane, drumming its way toward the south.

“I saw it rise,” said Joe. “It took off from one of those farms back of the village. It’s Ducroy’s crowd, sure as guns.”

“On their way to the flying field already. Well, we’d better be moving.”

They hurried down the street toward the hotel, where they had left the roadster. On the way, Frank told Joe the result of his telephone call. Joe too was disappointed that they had not been able to get in touch with Fenton Hardy.

“It means we have to play a lone hand, that’s all. What do you think we should do next, Frank?”

“I think we ought to tell the authorities.”

“We’ll warn them to watch the airplane hangars on the twenty-eighth and twenty-ninth,” said Joe. “But we mustn’t lose sight of Ducroy and his cronies.”

They looked back. The airplane was merely a blur in the distance. The boys realized that they had no time to lose. They scrambled into the roadster. Frank threw in the clutch and the car shot forward. Within a few minutes they were speeding down a road toward the south in the direction of the Riverside Field.

When the Hardy boys arrived at Riverside Field they looked in vain for Giles Ducroy and his friends. But the trio were not in sight, and there was but one airplane on the flying field. It was a small two-seater.

“It can’t be their plane,” said Frank. “Ollie Jacobs said it would hold four or five men.”

“Perhaps they haven’t arrived yet,” Joe suggested.

“They had only thirty miles to go. They should have been here long ago.”

“We can go up to one of the hangars and ask what planes have come in.”

Frank was dubious. “If Ducroy or any of the others are hanging around, we’ll be spotted. Our game is to keep out of sight.”

They sauntered over to the solitary little airplane in the middle of the flying field. A mechanic in grimy overalls was busy tinkering at the understructure of the machine.

“Is this the only plane here?” asked Frank politely.

The mechanic looked up. “It’s the only one out on the field,” he answered. “If you can see any more, let me know.” He grinned, and then waved toward one of the hangars. “An old crate just flew in a few minutes ago.”

“Where from?”

“How should I know? Airplanes, unless they’re on the mail run, aren’t like trains. Looked to me like a privately owned machine.”

The Hardy boys glanced significantly at one another. They had no doubt that this was Ducroy’s plane.

“Is the pilot in there now?”

The mechanic nodded. “Him and two other guys.”

Frank and Joe thanked their informant and made a wide detour across the flying field so as to approach the hangar at the far side. They had no desire to meet Giles Ducroy and his friends just now. They came around to the rear of the hangar without being observed and while they were looking about for a means of entrance other than by the front, Joe discovered a small door at the side.

He tried the door. It was unlocked. Joe edged it open and peeped in.

There was the plane, at rest in the hangar, and standing beside it were Giles Ducroy, Newt Pipps, and Ollie Jacobs. They were talking in low tones. Even as the boys watched they saw Ollie Jacobs move away from the others.

“It won’t take long,” he said. “I’ll do some telephoning and find out all I can.”

“Make sure of the date!” advised Ducroy.

Ollie Jacobs left the hangar. For a moment the Hardy boys were panic-stricken at the thought that he might look back and see them pressed against the side of the building, but Jacobs strode away without once glancing behind.

“I wish we could learn something definite,” whispered Joe. “This thing of following them around is beginning to get on my nerves. They are bound to catch sight of us, sooner or later.”

“We certainly can’t follow them around like this,” agreed Frank. “If they don’t see us, we’re liable to lose them anyway. If we can only find out what game they’re up to!”

They peeped through the opening in the door again. But Ducroy and Newt Pipps had withdrawn a little way to one side and were talking in undertones, their words inaudible.

In about ten minutes, Ollie Jacobs returned. He hastened into the hangar, and Ducroy looked at him expectantly.

“Well,” the boys heard Ducroy saying, “did you learn anything?”

“I sure did,” returned Ollie Jacobs. “It’s all settled. And we don’t have to wait as long as we thought we might.”

“That’s good,” declared Ducroy, rubbing his hands together with satisfaction. “What did he say?”

“The shipment will come on the night of the twenty-eighth.”

“As soon as that!” exclaimed Newt Pipps.

“We’ll be ready for it,” snapped Ducroy. “We’ll force him down not far from here.”

“It will be at night, eh?” said Pipps.

“Of course. All the better, too. I’d think twice before I’d try this trick in daylight.”

“I guess you’re right,” admitted Newt feebly. “Although I don’t like the idea of it at any time. You’re sure we’ll have only one man to handle?”

“Only one man. And there are three of us. We’re not taking a chance of failing.”

“How are we going to force him down?” asked Ollie Jacobs.

“Leave that to me,” answered Ducroy confidently. “There’s more than one way of doing that.”

“Let’s go and eat,” Newt suggested. “I’m half starved.”

“That’s a good idea,” Ollie agreed. “There’s a little restaurant near here. What do you figure on doing, Giles? Do you think we should stay right here at the airport until the twenty-eighth?”

“No,” said Ducroy firmly. “I don’t. The authorities are apt to find us if we stay in one place for any length of time. We’ll have to keep going. We’ll move around from one place to the other until the time comes. We can’t afford to be nabbed now. And after the twenty-eighth we’ll clear out for good.”

The three men moved up toward the front of the hangar, left the building, and went on across the flying field toward a small restaurant in the distance. There was a little lunch counter near by but the men ignored it for the more pretentious eating place.

Frank and Joe Hardy slipped quickly into the hangar through the side door. Instead of clearing up the mystery that puzzled them, the conversation they had just overheard confused them more than ever. That some criminal coup was in the wind for the night of the twenty-eighth was no longer in doubt, but what it was and where it was to take place still remained unrevealed.

“I don’t understand what’s happening,” said Frank, as he looked at the airplane in the hangar; “but I know we’ve got to be on hand if we can possibly manage it.”

“How can we be on hand if they’re going to keep flying from place to place for the next two days?” asked Joe.

“We’ve got to keep track of them somehow.” Frank moved about, inspecting the airplane. “I’d just like to reserve a back seat in this plane for the next forty-eight hours.”

“That idea isn’t as silly as it sounds!” declared Joe. “Why can’t we?”

Frank laughed. “How can we? They’d simply kick us out, for we’d certainly be seen.”

“Not if we went about it right.” Joe was excited as the possibilities of his idea became more apparent. “Why can’t we be stowaways? Don’t you remember the time we hid ourselves in the back of the automobile when we solved the Shore Road mystery? We could hide here too. I’ve heard of airplane stowaways before.”

“It’s a nervy idea,” said Frank. “I wonder where we could hide?” He moved down toward the rear of the plane. Suddenly he halted. “Just what we want, Joe! Here’s an opening.” He thrust the sliding door aside and looked into the dark interior. The tail of the plane was hollow and he could see a substantial hiding place. Considerable space was available for freight or baggage and, inasmuch as Ducroy and his friends were travelling light, there was plenty of room for the two boys.

“How about it?” asked Joe.

“I’m game. But how about food? We’ll be in there for quite a while, you know.”

“We’ll get sandwiches and water. Some blankets too, for that matter. We’ll simply stow away in there and make ourselves comfortable. Then, if anything happens, we’ll be right on hand.”

“We’ll be right on hand too if the plane crashes,” Frank reminded his brother. “Perhaps we’ll weight it down too much.”

“I don’t think so. This plane is designed to carry baggage, and if that space is empty, we’ll never be noticed. I think we can get away with it, provided we have any luck at all. It’s easily our best chance of keeping in touch with Ducroy and his gang. If they’re going to be flying around the country trying to dodge the authorities, we shan’t have much chance of keeping our eyes on them in our car.”

“That’s right, too.” Frank made up his mind. “I’m with you, Joe. And now’s our chance. Let’s get water and sandwiches and get into the plane while we have time.”

It seemed a mad scheme, but the brothers knew the importance of keeping close to Ducroy and his friends. Some crime had been planned for the night of the twenty-eighth, and the Hardy boys knew they must not lose track of their quarry for a moment. It would have been obviously impossible to follow the meanderings of the airplane from the ground.

They hastened over to the little lunch counter and laid in a stock of provisions. Several bottles of milk, a huge bottle of water, some cake and a stock of sandwiches constituted their supplies. At the lunch counter they spied two heavy automobile robes, and as it was too late to return to their own roadster, they bought the robes and entrusted the lunch counter man with the duty of driving their own car to a garage for safe-keeping. This he promised to do. Doubtless he wondered the reason for the boys’ purchases, but he was a man who believed in minding his own business and he exhibited no surprise or curiosity.

Frank and Joe hurried back into the hangar. They tossed the robes into their hiding place in the plane, arranged them comfortably, then stowed away the food and water.

“All set?” asked Frank finally.

“All set.”

Joe began to scramble into the plane.

“Just in time, too,” said the brother.

“Why?” asked Joe, in a muffled voice, as he crouched back on one of the automobile robes.

“Giles Ducroy and his friends are coming back across the flying field.”

Frank got into the plane. Quickly he closed the door. The two boys waited apprehensively. Had their presence been detected? Would the lunch-counter man mention having seen them? Would Ducroy glance into the baggage compartment before leaving?

But nothing happened. They heard the three men come into the hangar. They heard them moving about, evidently preparing for departure. Finally, they heard Ducroy’s voice:

“Get in. We’re away again.”

The plane was trundled out on the field. A moment later the motor roared, the machine bumped its way across the field, then the bumping motion ceased and the Hardy boys knew that they were in the air.

Although their flight as stowaways in the airplane was one of the most dangerous and perilous adventures that had ever befallen the Hardy boys, it was at the same time the most monotonous.

Back there in the darkness they could see nothing and they could hear very little except the roar of the engine. They were not uncomfortable and they did not suffer from lack of air, but it was not a pleasant sensation to reflect that they were high above the earth, wholly at the mercy of the rascals up in the front of the plane.

The plane dipped and rose, banked and turned. There were racks, presumably for the accommodation of baggage, to which the lads clung, so that at no time were they thrown off balance.

“If we get to tossing around in here, they’ll notice something wrong,” said Frank.

Their weight was evenly distributed and presumably Giles Ducroy did not see that his plane was somewhat tail-heavy. If he did, it is probable that he blamed the airplane itself, for it was strange to him.

After about an hour in the air, the boys were obliged to seize the racks, for the nose of the machine tilted downward and they were almost flung ahead as the plane descended. Finally there was a slight shock, and the plane bumped its way over a field. They could hear men’s voices, then the engine was shut off. They judged that Ducroy and the others were clambering out.

“Now,” they heard Ducroy saying, “I guess it’s safe enough for me to go and telephone.”

“Who are you going to telephone to?” asked Newt Pipps.

“I’m going to call up Jed. He’s at the Bayport airport. I’ll tell him to be ready for the night of the twenty-eighth so he can call us up when the time comes.”

“I don’t like the idea of having so many outsiders in on this,” Newt grumbled. “It means we’ll have to split the loot too many different ways.”

“Outsider!” snapped Ducroy. “Jed isn’t an outsider. How could we get along without him? We’re going to make a killing before long, and a lot of the credit will be due to him.”

“You’re right,” agreed Ollie Jacobs. “Shut up, Newt. We can’t get along without Jed. If you were half as much help as him we’d get along fine. You’re always kicking about something.”

This reprimand silenced Newt Pipps for the time being. The Hardy boys, listening, heard the three men move away.

When the footsteps and voices could no longer be heard, Joe heard Frank’s voice from the darkness:

“I wish I knew how long they’re going to be away. I’d like to get out of here and stretch my legs.”

“So would I. It’s mighty cramped in here. But if they’ve just gone to telephone I don’t think we should take the chance.”

Frank opened the door in the side of the plane and looked out.

“I can see them now. They’re walking across the field toward one of the hangars.”

“Where are we?” asked Joe.

Frank shook his head. “I don’t know. There seems to be a fair-sized town close by, but I’ve never seen the place before. I can see factory chimneys and church steeples.”

“Let’s have something to eat.”

Joe opened their package of sandwiches, a bottle of milk, and the bottle of water. Each ate of the frugal meal with enthusiasm, for they were hungry by now. When they had eaten they felt better, and in spite of the discomfort of their quarters they began to enjoy the novelty of the adventure.

“If only Chet and the other fellows could see us now!” said Joe.

“They’d be green with envy.”

“I’m not sure our position’s enviable.”

“We’re not out of the woods yet, by any means,” agreed Frank. “Ducroy and the others are apt to find us at any time. We’ll have to sit mighty tight.”

“If only we knew what they’re up to! It must have something to do with the Bayport air field. They’ve evidently got a confederate there, keeping in touch with him by telephone.”

“I think,” said Frank, “I’ll get out and stretch my legs a bit.” He opened the door a little wider and was just about to scramble out when he gave an exclamation and hastily drew back again, closing the door.

“What’s the matter?” whispered Joe.

“They’re coming back!”

Both boys were silent. They could hear voices, gradually growing louder. Frank wondered if he had been seen. Ducroy, Newt Pipps and Ollie Jacobs had not been more than a hundred yards away when he opened the door.

“There’s no room in the hangars,” Ducroy was saying, “but we’ll stay here overnight just the same. There’s a hotel not far from the field. Then, in the morning, we’ll get under way again.”

“What time?” asked Jacobs.

“About eight o’clock. We’ll have breakfast and then start again.”

“I don’t see why we can’t stay right here until we’re ready for the big job,” grumbled Newt Pipps. “What good does it do flying around from place to place?”

“If the police pick us up you’ll wish we had kept going,” declared Ducroy. “We can’t afford to be nabbed now. We’ve simply got to keep clear of the cops until the night of the twenty-eighth. After that we’ll scatter, and each take his own chance. The police will be looking for us hot enough then.”

“They sure will,” agreed Ollie. “Well, let’s go on over to the hotel. The plane is all right here, ain’t it?”

“Sure. It’s safe enough overnight. We’ll come back after breakfast and get under way again.”

The men moved off. After a while, when Frank Hardy peeped out again, he saw them going through a gate on the far side of the flying field, evidently heading toward the town. He breathed a sigh of relief.

“That’s a bit of luck,” he said to Joe. “We don’t have to stay cooped up in here all night. As long as we get back here well before they show up in the morning everything will be fine.”

“Where can we stay? We can’t go to the hotel. I don’t think it’s even wise to go into the town at all. If they ever catch sight of us it will spoil everything.”

Frank scrambled out of the plane. He walked about, enjoying the feel of solid ground beneath his feet again. Joe followed, and immediately turned a handspring to express his delight.

“Makes you feel good, doesn’t it?” said his brother, grinning.

“I’ll tell the world it does, Frank! Gee, I feel as cramped as a sardine in a tin.”

“So do I.” Frank stretched himself. “Say, we were mighty lucky they didn’t discover us.”

“Right you are. If they had—well, there is no telling what they would have done.”

“They might have killed us, Joe.”

“Oh, maybe not as bad as that. But they might have tied us up in the woods and left us there.”

“They are a bad crowd.”

“I agree with you.”

The brothers took a look at their surroundings from every side.

“We’d better move away from the plane,” advised Frank. “Some of the mechanics at the hangars may see us and tell Ducroy. I think our best bet is to go to that farmhouse on the other side of the field.”

“Perhaps we can use the telephone there, if they have one.”

In the fading light, the boys crossed the field, climbed over the fence and made their way toward the farmhouse. As they entered the barnyard, a collie dog ran toward them, barking. He was a friendly animal, however, and as he approached he wagged his tail and fawned on them. A stout, cheery-looking man was standing in the doorway of the house.

“Hello, boys,” he shouted. “What can I do for you?”

“Have you a telephone?” asked Frank.

The farmer nodded. “You’re welcome to use it,” he said, then added: “As long as you pay the charges.”

“We’ll do that all right.”

The farmer led them into the house and indicated the telephone in the hall.

“Talk away,” he said. “I saw you coming over from the flying field,” he remarked shrewdly. “Why didn’t you use the telephone there?”

“Private reasons,” replied Joe.

The farmer did not move away while Frank put in a call for Chief Collig at Bayport. At mention of the chief’s name he seemed interested, and when Frank finally got the chief on the wire, he listened with all his ears.

“Chief Collig?” asked Frank. “This is Frank Hardy speaking.—No, we haven’t jumped bail.—What’s that?—We’ll be back in good time.—The reason I’m calling you is to warn you to keep a good watch on the airport on the night of the twenty-eighth.—I can’t tell you why.—There is going to be some trouble.—I don’t know anything more about it than that.—It will be worth your while to make use of this warning.—Where am I speaking from? I can’t tell you. And listen, Chief, will you call up my mother by telephone and let her know that I called you and that Joe and I are all right?—Thanks. Good-bye.”

When Frank rang off, he saw that the farmer was regarding him curiously.

“Looks as if you boys are smarter than you seem,” he remarked. “What are you? Detectives?”

“I suppose you might call us that,” admitted Frank. “But we’d be obliged if you would say nothing to anyone at the airport about us.”

“You can trust me,” returned the man. “I can keep my mouth shut. Where are you staying to-night?”

“We don’t know yet,” said Joe.

“If you’d like to stay here, we have a spare room, and you’re welcome to it,” the farmer volunteered.

“That’s mighty good of you. We were just wondering where we would find a place to sleep. We have to be up and out by seven o’clock, though.”

“I get up at five, myself,” laughed the farmer. “Come on into the kitchen and I’ll have my wife fix up something to eat. You’re more than welcome to stay with us overnight. I’m dyin’ to know what you lads are up to, but I guess I’d better not ask too many questions.”

“You’ll read all about it in the papers,” laughed Frank, “if everything works out the way we want it to.”

The next day was the twenty-seventh and the Hardy boys knew that they had another day to put in before Ducroy and his friends would be ready for the mysterious coup for which they had laid so many plans.

Frank and Joe were up early, and after a substantial breakfast at the farmhouse they said good-bye to the good-natured farmer and his wife, then hastened across the fields toward the airport again. There were a few signs of life about the hangars; some mechanics were busy at a plane out in the field; a new machine was preparing for a take-off. But the Ducroy plane was deserted and the lads saw that they were in good time to conceal themselves again.

With a fresh supply of water and sandwiches which they had obtained at the farmhouse, they went casually over to the plane, looked around to see that they were not observed, and then, when the coast seemed clear, they slipped quietly into their hiding place.

“Another day ahead of us!” said Frank. “I wish this was the morning of the twenty-eighth instead of only the twenty-seventh.”

“We’ll get through somehow. I hope they don’t keep flying around all day. It gets mighty monotonous being cooped up like this in here.”

Frank made himself more comfortable on his automobile robe.

“We could be worse off. We have lots to eat and drink, and we don’t have to worry about steering the plane.”

“I like to see where I’m going,” said Joe dubiously.

“As long as Ducroy stays sober he isn’t a bad pilot,” returned Frank. “I guess the other pair will see that he’s fit to take the controls before they’ll fly with him. Their necks are just as precious to them as ours are to us.”

“Guess we’d better keep quiet now. They may be along any minute.”

The lads lapsed into silence. In about half an hour they could hear voices and then came footsteps.

“Just a short jump to-day,” they heard Ducroy saying. “Just a short jump, and then we’ll lay low until to-morrow night.”

“Where are we going?” asked Newt Pipps quickly.

“You’ll know when we get there.”

“I wish we could have stayed here,” insisted Newt. “I could have stood another two hours’ sleep easily.”

“If we stick around here we’ll be liable to find ourselves sleeping in jail,” said Ollie Jacobs. “I got the scare of my life when that cop came up and spoke to us.”

“I thought we were sunk,” admitted Ducroy. “He had been eying us for quite a while and I was getting nervous. I was sure he had spotted us.”

“You stood him off all right. That was pretty good, telling him we were stunt pilots on our way to Hollywood. He swallowed it, hook, line, and sinker.”

“Just the same,” observed Ducroy, “you see how easy it is to run into trouble. If that cop had been a little wiser we might have been in the jug right now. And if he starts talking to some other cop and describes us, we may find ourselves in trouble yet. So the sooner we get out of here the better.”

This sentiment seemed to find favor with the others, for there was considerable bustling around as they prepared to take off again. In due time the propeller began to whirl, the engine burst into a roar, the plane quivered. The boys heard a shout from Ducroy, and then the airplane moved slowly off across the field.

It bumped and rocked along, its progress becoming smoother as it gathered speed; then it left the ground, the body of the plane tilted a little as it began to climb. After a while it banked, circled about, then straightened in swift flight.

It was hot and stuffy back in the compartment where the Hardy boys had hidden themselves, but they comforted themselves by remembering that Ducroy had said this was to be only a short jump. After that, the rascals evidently planned to lie in hiding until the night of the twenty-eighth.

The plane drummed along at a good speed for some time. Then the nose dipped so suddenly that the lads were flung forward. Their weight being thrown ahead, the tail was suddenly lighter and the plane went into a sudden dive. They heard a yell of alarm from one of the men in the forward part of the machine, but the plane straightened out as swiftly as it had lost balance. Frank and Joe had been frightened for the moment but they soon regained their accustomed positions again and clung tightly to the racks while the plane descended in sweeping circles.

It went into a long glide finally, then the wheels bumped against the ground. It rose into the air, bumped again, then taxied across a field until it gradually came to a stop. The motor was suddenly shut off.

“What happened?” they heard Newt Pipps shout in alarm.

“Lost control there for a minute,” Ducroy answered. “She went into a dive a lot faster than I had figured on.”

“I thought we were going to crash,” declared Newt shakily.

“Not with me at the controls,” boasted Ducroy. “I don’t know what went wrong, but it didn’t take me long to straighten her out.”

“It was just as if we had some baggage in the back and it shifted forward,” said Ollie Jacobs.

The Hardy boys were breathless with apprehension. Perhaps Ducroy would be tempted to investigate!

“Well, there’s no baggage,” insisted Ducroy. “It’s just the plane. I’m not quite used to it yet.”

“I’ll be glad when this business is over,” said Newt. “I don’t like this flying business, anyway. Solid earth is good enough for me any day. When this job is over and I get my share of the money it’ll be a long time before anyone tempts me into an airplane again.”

“Where are we now?” asked Ollie. “This isn’t a flying field.”

“It’s better,” returned Ducroy. “This is an abandoned farm. We’re quite safe here. If anyone comes to investigate, we’ll just say we ran out of gas and have to wait here for a while until we get a fresh supply.”

“We’ll stay here until to-morrow night, then?” asked Newt.

“There’s a little village about a mile away. We can go there and stay overnight and loaf around to-morrow. It’s a lot better than hanging around a flying field where people are apt to ask questions.”

“This suits me all right,” said Ollie Jacobs. “I didn’t like the idea of hopping around from place to place the way we were doing. The plane is safe enough here, I guess.”

“A few farmers may drop around to have a look at it, but I don’t think there’s any danger of anyone stealing it,” said Ducroy. “We might as well go on into the village.”

“I’m hungry,” declared Newt. “This flying gives me an appetite. Let’s go and get something to eat.”

The Hardy boys listened as the voices diminished in the distance. When they could no longer hear the trio, Frank opened the side door and peeped out. He could see Ducroy and the others climbing over a fence at the other side of a wide field. The men went out to the road and then trudged on toward a little village lying in a hollow about a mile away.

The boys breathed sighs of relief as they scrambled out.

“This is luck!” said Frank. “No more flying until to-morrow night.”

“I hope we don’t have to stay inside the plane until then. Those fellows are apt to come back at any minute.”

“I don’t think so. You heard what they said. They intend to stay here until to-morrow night. As long as we show up here in good time to hide ourselves before they leave, we’re all right.” Frank strode up and down the field, taking the kinks out of his legs. “Let’s take our sandwiches and go over to that abandoned farmhouse. We can stay there quite comfortably until it’s time to leave.”

Joe agreed. “We’ll have to keep an eye on the road. We can’t afford to let them see us getting into the plane and we can’t afford to let them start without us.”

“We’ve stayed with them so far and we’ve got to stay with them to the finish,” declared Frank. “I only wish we knew where this business is going to end.”

They took their package of food from the plane and went across the field toward the farmhouse. It had been abandoned for some years and was in a bad state of repair, but it sufficed for their purpose. The boys spent the greater part of the day exploring the place, and toward mid-afternoon Frank suggested that they might as well sleep there that night. They went back to the plane, which had been undisturbed, and removed the automobile robes, bringing them back to the house.

“We’ll have to sleep on the floor to-night,” laughed Frank.

“I don’t care where we sleep, as long as we get these rascals where we want them.”

They found a spring down in the orchard, and the cold spring water served to make more palatable the sandwiches the farmer’s wife had made for them that morning. Toward evening they went into one of the upper rooms of the house and looked out over the field toward the plane. There they saw three figures walking across the field.

“I hope they’re not going to start off again,” said Joe, in alarm.

“They’ve probably just come back to see if the plane is all right.”

The three men were Giles Ducroy and his companions, and their errand was evidently as Frank had suggested. Ducroy went over the plane very carefully. Then he went toward the back and suddenly pulled open the door in the side. The boys saw him peer into the interior of the plane.

“Boy, isn’t it lucky we didn’t stay there!” exclaimed Joe.

“I hope he doesn’t find that water bottle. We left it there. Remember?”

But Ducroy’s inspection was brief. He drew back, closed the door again and turned to the others with an expressive gesture. Frank and Joe realized that he had merely made the inspection to satisfy the others that there was no baggage in the plane. Evidently the water bottle had gone unnoticed.

The trio stayed only a few minutes, then went back across the field again toward the village.

“That’s that!” said Frank. “We’re all right now until to-morrow night. We’ll go over some time in the afternoon, hide ourselves and then wait for things to happen.”

The boys stayed in the empty farmhouse that night, and they slept soundly in the automobile robes, despite the hardness of the floor. The gray light of dawn was just shining through the window when Frank heard a sound that awakened him with a start.

It was the throbbing roar of an airplane engine!

He got up and scrambled over to the window. When he looked out he was just in time to see a figure clambering into the cockpit of the plane out in the field. Then the machine began to move across the pasture; its speed increased; it rose from the ground, skimmed above the fence, rose higher and higher into the air and then headed far off beyond the village.

Joe, in the meantime, had been aroused by the noise of the engine, and he too witnessed the airplane’s flight.

Disheartened and discouraged, the boys looked glumly at one another.

“I guess that means we’re licked,” said Joe, at last.

After all their precautions, the sailing away of the airplane without them was a bitter pill to swallow. The Hardy boys had been so confident that the men would remain in this place until the night of the twenty-eighth that this early morning flight took them completely by surprise.

“We’ve lost them now,” said Frank. “We don’t know where they’re going or where this hold-up, or whatever it is, is going to take place. And we don’t even know where we are ourselves.”

“It’s tough luck. After all the trouble we went to!”

“I guess the only thing we can do now is go back to Bayport and do our best to warn the post office authorities. I have a pretty good hunch that the gang are planning another air mail robbery. Why else would they use a plane?”

“Not much use staying here,” agreed Joe. “They certainly stole a march on us that time.”

They got dressed and left the empty house. Neither said very much, for they were discouraged beyond measure. All their discomfort of the past two days seemed to have gone for nothing. They realized that the defeat was not their fault, because they could not anticipate that Ducroy and his cronies would leave that morning when they had definitely planned to remain in the vicinity all day; but there remained the unescapable fact that the quarry had eluded them.

“Perhaps the police in the village recognized them and they had to clear out,” suggested Joe.

“I guess that’s the reason. I can’t think of any other.”

They trudged down the lane that led out toward the village road. Their immediate plan was to reach the village, find out where they were, and then return to Bayport as soon as possible.

“There’s just a slim chance we may be able to catch them yet if we tell the post office authorities all we know,” Frank pointed out. “But we haven’t much time to work in.”

The sky was overcast and cloudy that morning, in harmony with the mood of the Hardy boys. They found it difficult to be cheerful after the reverse they had just suffered.

“I’ll bet there isn’t even a railway here,” grumbled Joe.

“And our roadster is miles away.”

“What a fine fix we’re in!”

“Perhaps they’ll come back,” remarked Frank, trying to be optimistic.

“They’re gone for good.”

The Hardy boys crossed a rustic bridge over a stream and went up the dusty road into the village. It was only a small farming town and there were few people in sight. Several cars were parked in front of the small hotel.

“We might as well go in here and have breakfast,” suggested Joe. “Our sandwiches are all gone.”

They went into the hotel and entered the dining room. In spite of the disappointment they had suffered, their appetites still held good and they managed to make away with a goodly supply of ham and eggs, flapjacks and syrup, toast and coffee. The meal over, they felt better. After paying the check at the desk, they sat down to consider future plans.

The clerk told them that the village was about one hundred miles from Bayport, and that the nearest railway was four miles distant. If they hired a man from the garage to drive them to the station they could catch a train that would bring them to Bayport late that afternoon.

“I guess it’s the best we can do,” said Frank. “Mighty flat ending to our adventure.”

“Perhaps it isn’t over yet.” Joe was looking out into the street. Suddenly he clutched his brother’s arm. “Look, Frank! Do you see what I see?”

Frank looked out. He gasped with astonishment.

Across the street, lolling in the doorway of a grocery store, was a familiar figure. There was no mistaking the battered hat, the shabby clothes, the mournful and unshaven features.

“Newt Pipps!”

“He’s still here.”

At that moment the Hardy boys were perhaps the most delighted and amazed lads in the United States.

“They left him here,” said Frank. “Why, this means the others will be coming back!”

“Unless they’ve ditched Newt altogether.”

“They wouldn’t do that,” said Frank, meeting Joe’s objection. “He knows too much. He knows all about this crime they have been planning. Ducroy and Ollie Jacobs would be afraid to get rid of him now.”

“That’s right, Frank. We gave up hope too quickly. The other pair will probably be coming back to the farm to-day.”

“We’d better get back there just as quickly as we know how. We don’t want to be caught napping now.”

Newt Pipps was still standing in front of the grocery store. Apparently he had no intention of moving on. The Hardy boys knew they were risking discovery if they went out the front entrance, so they scouted around until they found a back door to the hotel and departed unobtrusively. They cut across the yard, went down a lane, and soon found themselves on the road leading back to the farm.

They were about half way back to the farm when they heard a distant droning noise. Frank looked up.

“Here comes the plane!”

A speeding shadow in the sky quickly resolved itself into the shape of an airplane, which gradually approached and began to descend in wide spirals. The boys left the road and took to the shadow of the trees, for although they knew there was little chance of being recognized from the air, they were taking no risks. The plane came lower and lower, then skimmed across the fences, coming to rest in the field near the old farmhouse.

“If this isn’t luck!” exclaimed Frank.

“They probably went away to get gas and oil. Now, if they’ll only give us a chance to get back in our hiding place again everything will be all right.”

They went on cautiously, toward the field. They had just come to the entrance of the lane leading down toward the farm when they heard voices. Frank and Joe scrambled into the hedge and hid themselves.

They were not a moment too soon.

Giles Ducroy and Ollie Jacobs clambered over the fence, only a few yards away.

“Everything is all set now,” Ducroy was saying. “We’re all fueled up, the plane is in first-class shape, and we’re all ready for the big job.”

“We’ll go back and pick up Newt now,” said Ollie Jacobs.

“He gives me a pain,” grumbled Ducroy. “If it wasn’t that he has been with us from the start I’d be tempted to drop him right now. Imagine being too frightened to go on that flight with us this morning.”

“Newt is yellow.”

“He certainly is. Well, as long as he comes with us to-night and does his part, I don’t care how yellow he is about flying.”

“Shall we come back here right away?”

“No. Some of these villagers might get suspicious. We’ll hang around town until it gets dark. Then we’ll set out. I know the exact time and place we can count on meeting this fellow and the whole thing ought to be over in twenty minutes.”

“Good,” said Jacobs.

The two men went on down the lane. They had not seen the Hardy boys hiding in the hedge. When they reached the road they turned in the direction of the village and in a few moments were lost to view.

Frank and Joe crawled out of the hedge.

“On the trail again,” said Frank.

“We shan’t have to stay hidden in the plane, after all. This is luck.”

They hastened down the lane to the farmhouse. Unwittingly, the rascals had played into their hands. They now knew that Ducroy would not start on the mysterious mission until after darkness had fallen, and they resolved to be in readiness.

“Just when we had given up hope,” said Frank, “everything gets clear again!”

“Clear enough so far,” agreed Joe. “We won’t take any chances on slipping up again. We’ll be hiding in that plane at sundown.”

The boys went back to the house and there they remained for the rest of the day. They found that from one of the upper windows of the building they could have an uninterrupted view of the road leading to the village, and they made frequent visits to this window in order to make sure that Ducroy and his companions would not steal a march on them. However, the afternoon dragged past with no sign of the trio, and it was evident that they were following their original program of loafing about the village.

The airplane, which had evidently escaped notice, rested alone in the field.

Toward the latter part of the afternoon the clouds which had been gathering all day gathered overhead and there was a light shower of rain. It passed over, but the weather became cool and blustery.

“A bad night for flying,” remarked Frank.

“If Ducroy can chance it, so can we.”

“That’s right. I hope they don’t call it off.”

“Not after waiting this long,” said Joe. “Ducroy has set his heart on this affair. It’ll take a mighty stormy night to make him quit at the last moment.”

The afternoon seemed endless, but at last Frank turned to his brother.

“We may have quite a while to wait, but I think we ought to go over to the plane now.”

“I don’t mind waiting. I’d rather wait an hour or so than be left behind, as we thought we were this morning.”

“Let’s go, then.”

The boys left the house and went over to the field. The airplane was apparently just as Ducroy and Jacobs had left it. There was no sign of anyone on the village road.

The Hardy boys climbed into their hiding place and made themselves as comfortable as possible. For the time being, they left the door open for the sake of fresh air. Minutes went by. The sky grew darker and the wind rose. Once in a while a gust of rain spattered against the wings of the machine.

At last Joe crouched forward.

“Here they come! I see a light down the road.”

He reached out and closed the door.

Breathlessly, the Hardy boys awaited the next move in their perilous adventure.

The Hardy boys soon heard footsteps as the three men approached the plane.

“I wish the weather was better,” Newt Pipps complained. “I’m afraid something will happen.”

“I wish you’d keep quiet,” snapped Ducroy. “If you’re so scared why did you come in with us at all?”

“I need the money.”

“And you don’t want to earn it. I’m doing all the work. All you and Ollie have to do is throw the ropes over the side when I give the word then get your guns ready for the hold-up.”

“We may lose him in the dark,” whined Pipps.

“I know every foot of his route,” returned Ducroy. “He’ll come right over the two church steeples in Jasonville, then strike west of the light on Bacon Hill.”

These places were new to the Hardy boys. They had never heard of either Jasonville or Bacon Hill. They listened while the trio made the final preparations for flight. It did not take long. In a few minutes they heard the propeller whirring. The engine roared, there were a few shouts as the men took their places, and then the plane bumped off over the uneven ground.

It gathered speed, then the bumping ceased as the plane rose. It cleared the fence at the end of the field, circled somewhat slowly, and rose higher.

For a time the plane flew a direct course, then it banked and circled. There was no doubt in the minds of the Hardy boys now that Ducroy and his companions meant to hold-up another airplane, but how this hold-up was to be managed they had not the least idea. It was very confining inside the body of the plane, for the night was hot and sultry despite the rain. The roar of the engine drowned out all other sounds.

Suddenly the plane dipped. Joe, who had relinquished his grip on the rack, was thrown forward. The machine lost balance and nosed down accordingly. Ducroy quickly straightened it out and Joe tried to edge back toward his brother in the darkness.

He found, however, that his wrist was tightly held.

Panic-stricken, he groped forward. His shirt sleeve had been caught in the steering gear running from the controls back to the rudder at the tail of the plane.

While he tried to extricate himself the plane began to buck and sway in the wind.

Frank, realizing that something was wrong, switched on a small flashlight he had with him, and moved slowly forward. The beam of light fell on Joe’s shirt sleeve. When the boys saw what was wrong they made desperate attempts to release the sleeve, but it was now firmly entangled in the gear.

Suddenly the roar of the motor died. Ducroy had shut off his engine. The plane was nosing down toward the earth in a thrilling dive. Wind sang in the struts.

“What’s the matter?” shouted Newt Pipps, in terror.

“Steering gear jammed!” answered Ducroy sourly.

“We’ll be killed!”

“Hold steady, you fool!” growled Ollie Jacobs. “What’s the matter, Giles, can’t you get her out of it?”

Ducroy was working frantically at the controls.

“Something wrong somewhere. This old bird’s tail is as heavy as lead. I can’t move the rudder.”

The gear was moving in response to his efforts at the controls. Frank seized Joe’s sleeve and gave a quick wrench. The movement of the gear had loosened the sleeve somewhat and it abruptly came loose.

At the same moment there was a shout of satisfaction from Giles Ducroy.

“She’s working again. Say, next time I land I’m going to see if we haven’t some ballast aboard. There’s something radically wrong back there.”

“We won’t need the plane after this haul,” declared Jacobs. “If we get through this trip all right we’ll be set for life.”

The Hardy boys scrambled back to their places. The nose of the plane suddenly raised. The engine began to roar again. Ducroy then brought the machine out of its breath-taking dive. It flattened out and raced on again.

Frank and Joe were panting with excitement. Each realized how near they had been to death. With the rudder useless, the plane would have crashed nose down into the earth and they would have perished instantly.

From then on, the boys clung to the rack with every movement of the plane. That one hazardous experience had been sufficient warning.

Suddenly, above the noise of the engine, the Hardy boys heard a shout from one of the men. Then they became aware of a new sound. A steady, distant drumming was apparent.

“The other plane!” they reflected.

The machine banked, swept about in a great circle. The big moment was at hand. The drumming of the other plane became clearer.

“Stand by!” they heard Ducroy yell.

The plane bucked as it was caught in a gust of wind, then it shot forward and began to climb. The drumming of the other plane was now quite audible, mingling with the roaring of their own machine. It seemed to be below them and in front of them.

Ducroy was evidently jockeying for a strategic position, for the plane rocked and swayed, banked and turned, dipped and rose again.

“Ready!”

There was an answering shout from Ollie Jacobs.

“Over she goes!”

The boys heard a rattling sound from the forward part of the plane. What it was they could not imagine.

An instant later, the drumming of the plane below ceased abruptly.

Their own plane swung around. Ducroy cut off his engine and went into a dive.

“We’ve got him!” they heard Ollie Jacobs shouting. “There he goes. Look! He’s diving.”

“Don’t lose sight of him!” shouted Ducroy.

“He’s heading for a field. Nose her down. We’re right behind him, Giles!”

The plane dived swiftly.

From below, the boys heard a distant crash.

“He’s on the ground. Watch out, Ducroy. Come up behind him.”

The plane banked, flinging the two boys violently to one side. It lurched, dived again unsteadily.

“Get ready!” ordered Ducroy. “Don’t let him get away. Can you see him, Ollie?”

“I can’t see him, but I can see the plane. It’s right ahead. Get your gun, Newt.”

“I’m ready,” quavered Newt Pipps.

Gradually, the plane settled down. There was a bump as the wheels touched the earth. The plane rebounded high into the air, for Ducroy had slightly miscalculated in the darkness. The engine roared again. The wheels once more touched the ground, and the plane rocked on over the uneven surface. Finally it came to a stop. The Hardy boys heard a scrambling from the front of the machine.

“All out!” Ducroy was shouting. “Now, boys, make quick work of this. Grab the bags and get back here as quickly as you can. Don’t waste any time. Get into the plane again and wait for me. I’ll get back and start her again. We’ll be in the air before he knows what it’s all about.”

The Hardy boys could hear them running across the field. Frank reached for the catch, flung the door open. He and Joe scrambled out of the plane.

The scene was illuminated by a cloudy moon. There was just sufficient light for them to see a wrecked and crumpled airplane in the field some distance ahead. A pilot was painfully extricating himself from the wreckage. Ducroy and the others were running toward him with drawn revolvers.

The Hardy boys, too, were armed. Realizing that their antagonists were desperate men, they had taken the forethought to provide themselves with revolvers before leaving Bayport. Each lad gripped his weapon.

“It’s the hold-up!” said Frank quickly. “Let’s break it up.”

“Just a minute!” declared Joe. “They want to get away in this plane. If we can’t handle them they’ll make a getaway in spite of us. Let’s fix it so they can’t.”

He ran toward the front of the plane, scrambled up into the cockpit. Joe knew something of machinery, and it took him only a few seconds to break an important wire connection that rendered the engine useless for the time being.

“That’ll fix ’em,” he said jubilantly, as he ran back to Frank, who was waiting impatiently. “Now we can take a hand in this little game.”

They ran toward the wrecked plane just as Ducroy and his cronies leveled drawn revolvers at the pilot.

“Put up your hands or we’ll shoot!” ordered Ducroy.

Caution prevented the Hardy boys from going closer to the fallen plane.

They had not been seen by Ducroy or the others, and they now realized that it would be folly to play into their hands at this moment. They were outnumbered and they saw that they might easily be disarmed if they took reckless chances. Frank suddenly halted and grasped Joe by the arm.

“We’re foolish to come out in the open like this. We’re just as liable to be shot.”

“That’s what I’ve been thinking,” replied Joe. “What do you think we’d better do?”

“They’ll be coming back to the plane. I think we ought to wait here for them and hold them up when they come back. They’ll be off their guard then and probably they’ll be loaded down with stuff from the other plane.”

Without further parley, the lads turned and ran back. In the gloom they had not been seen. They crouched in the shadow of the disabled plane and watched the activities of the others.

The pilot, after his first shock of surprise, had quickly thrown up his hands. Ducroy and the others advanced toward him.

“What’s the idea?” the lads heard the pilot saying.

“We haven’t time to talk to you,” growled Ducroy, holding a revolver against the man’s body. “We want those mail bags you have here.”

“Bandits, are you?” snapped the pilot “You’ll suffer for this. You tried to kill me!”

“You’re not dead yet,” said Ollie Jacobs callously.

“You flung a rope down from your plane and it tangled up in my propeller shaft. It’s just by luck that I wasn’t killed in the crack-up. Just wait. You’ll pay for this night’s work.”

“We’ll get paid,” chuckled Ducroy. “Get in there, Newt, and heave out those mail bags.”

The pilot was helpless under the menace of the drawn revolvers. He was forced to stand by while Newt Pipps scrambled into the plane, found the mail bags, and began throwing them out to the ground.

“I’ll take care of this fellow,” said Ducroy. “Ollie, you can start bringing those bags up to the other plane. Work fast. Some of these farmers around here may have heard the plane crash and they might be along any minute to investigate.”

Ollie Jacobs, pocketing his revolver, sprang forward and seized two of the heavy mail bags. He flung them over his shoulder and hastened back toward the plane, where the Hardy boys awaited him.

Nearer and nearer he came. The boys crouched in readiness.

Jacobs reached the plane. He did not see the lurking shadows. He was just reaching forward to open the door of the baggage compartment for the reception of the stolen mail bags when Frank Hardy stepped out and swiftly pressed a revolver against his side.

“Up with your hands, Jacobs! Not a word out of you!”

Ollie Jacobs gave a strangled exclamation of surprise. Then he dropped the mail bags. His arms shot into the air.

“Who—who are you?” he stammered.

“Keep quiet! One word out of you——” Frank prodded him with the revolver to emphasize his command.

Ollie Jacobs was frightened into silence. From where they were standing, the scene could not be observed by Ducroy. Frank and Joe backed their captive up against the side of the plane and bade him be quiet.

A moment later they heard Ducroy shouting.

“Ollie! What’s keeping you? Hurry back here and get these other bags.”

Jacobs stirred restlessly, but Frank jammed the revolver against his ribs. He was helpless, and he knew it.

“Ollie!”

Ducroy was becoming angry.

“What on earth has happened to him? Here, Newt! Keep this man covered while I go and see what’s the matter.”

A moment later the Hardy boys heard Ducroy running toward the plane. He came around the side, muttering to himself. Joe was waiting in readiness. He leaped out and thrust his revolver against Ducroy’s chest.

“Hands up, Ducroy!”

Ducroy gave a shout of dismay, stepped back, but when he saw the revolver he raised his arms.

“Get back over here beside Jacobs.”

Reluctantly, Ducroy did as he was told. Frank went swiftly through the pockets of each man and disarmed them both.

“Now,” he said to Joe, “if you’ll keep this pair covered, I’ll go back and attend to friend Newt.”

Joe, with a revolver in each hand, eyed his captives warily. But Ducroy and Jacobs, unarmed, had too much respect for the menacing weapons and the determined boy who held them, to make any rash break for liberty.

Frank, his revolver in readiness, went over toward the other plane where Newt Pipps was holding the pilot at bay. At the sound of his footsteps, Newt called out:

“What’s the matter, Ducroy? I thought I heard you shout.”

“Everything’s all right,” growled Frank.

Apparently, Newt was deceived, for he did not look around. It is certain that he got the shock of his life when he felt a revolver muzzle pressed against his back and heard a stern voice say:

“Up with your hands, Newt! Drop that gun immediately!”

With a squeal of amazement, Newt Pipps whirled around, lowering his weapon as he did so. At the same moment the pilot, who had been watching his chance, sprang forward, seized the fellow’s wrist and wrenched the weapon from him. There was a brief struggle, and Newt Pipps was overpowered.

“The others are back at the other plane,” Frank told the pilot. “My brother has them covered.”

“Good!” said the aviator, dealing Newt a hearty kick. “Now get along there, you!”

They propelled the luckless Newt ahead of them across the field until they reached the other plane, where they found Joe still on guard over his captives.

“Try to rob the air mail, would you?” gloated the pilot, as Newt was lined up beside the others. “You mighty nearly got away with it, too. But not this time!”

Ducroy leaned forward, peering at his captors in the gloom. It was then that he recognized the Hardy boys.

“I thought so!” he muttered bitterly. “The Hardy boys! Although how on earth the two of you got here is beyond me.”

“This means jail!” moaned Newt Pipps. “Oh, why did I ever let myself be argued into this! I knew we’d never get away with it! I said so from the start!”

“Shut up,” snarled Ollie Jacobs. “Shut up and take your medicine like a man. We’re licked; but we would have been well away if it hadn’t been for those Hardy boys.”

“You lads certainly came along in the nick of time,” said the pilot of the mail plane. “You couldn’t have got here better if you had planned it from the start. There is about fifty thousand dollars in cash in those mail bags. That’s what this gang were after. They circled my machine and dropped a tangle of ropes over the propeller. I had to make a landing, and nearly lost my life in the bargain.”

“We did plan it from the start,” Frank told him quietly. “We have been following these men for three days, trying to find what they were up to.”

“Following us!” cried Ducroy. “How could you follow us? We’ve flown hundreds of miles in the last three days.”

“And we flew with you. We’ve been quite comfortable back in the tail of the plane.”

A startled exclamation burst from Ducroy.

“So that’s what was wrong! I thought there was something mighty queer about the way that machine was acting. And I never even looked! The two of you right on our trail from the start!”

His ejaculations of surprise and disgust were echoed by Ollie Jacobs and Newt Pipps. As for the pilot, he was hilarious in his admiration of the Hardy boys.

“You were trailing them all the way!” he exclaimed. “Well, that’s the best I’ve ever heard. And they thinking they’d make a neat clean-up! Boys, when I report this to the post office department you’ll hear some fine things said about yourselves for this night’s work.”

Joe rummaged about in the plane and found a length of rope. He cut this into convenient pieces, and while Frank covered the three bandits with his revolver, Joe and the pilot made quick work of binding them hand and foot.

The trio had just been safely trussed up when they heard the clatter of an automobile in a road near by, saw the beam of headlights, and then they heard a hoarse voice:

“What’s going on over there?”

“Who are you?” shouted the pilot.

“I’m the sheriff of this here county, and I want to know what monkeyshines are going on over there. I have a shotgun with me, and I’m ready to use it; hurry up and answer.”

“You’re as welcome as the flowers in May, sheriff,” yelled the pilot jubilantly. “Come along with your shotgun. We’ve got some prisoners here for you.”

Beyond an occasional robbery of a hen roost the worthy sheriff had experienced few cases of crime in the county during his time of office, and when he discovered who the prisoners were and why they had been captured he was one of the most astounded and bewildered men in the world.

“Robbin’ the air mail!” he stammered. “Why, these fellers must be desperate criminals!”

“They’re not very desperate now, sheriff,” laughed the pilot.

“What d’you want me to do with ’em?” asked the man of the law doubtfully.

“Lock ’em up.”

“I don’t know as I’m responsible.” The sheriff was not anxious to be given charge over three mail robbers.

“You’re responsible, all right, until the government takes them off your hands,” returned the pilot abruptly. “You take these men and lock them up in your village jail, and make mighty sure they don’t get away from you, either. This crime took place in your county, so you can just get busy and do your duty.”

The sheriff looked very unhappy about it, and kept Ducroy and his companions carefully covered with the shotgun, as though fearing they might break loose at any moment. Assistance soon arrived, when a number of farmers and people from the village, attracted by the crash of the mail plane, came clambering over the adjacent fences. In a remarkably short space of time a crowd had collected. Everybody talked at once, everybody asked questions, and general excitement prevailed.

“What’s the excitement?”

“Airplane busted, eh?”

“Anybody killed?”

“Gosh, Jed, look at the sheriff! What’s he up to, anyhow?”

“Don’t know nothin’ ’bout it, Asa. But somethin’ is plumb wrong, that’s certain.”

“Don’t go too close to the shebang, Billy, she might bust up on you.”

“First time I ever did see an airplane come down like that.”

“Me, too. Glad I come along just in time. I wouldn’t go up in one of ’em for a million dollars.”

“Nor me.”

The sheriff, becoming bolder, announced to all and sundry that he had just captured three mail robbers at great risk of his own life and called on his fellow villagers to help him take the trio safely to jail.

Ducroy, Ollie Jacobs, and Newt Pipps were consequently surrounded and led out of the field, bundled into an automobile where they were guarded by the sheriff, armed with his shotgun, and two husky villagers armed with clubs, then hustled off to town.

The pilot turned to the Hardy boys. A number of people had remained at the scene and were busy inspecting the wrecked plane and asking questions. The majority of the villagers, however, had hastened in the wake of the sheriff and his prisoners.

“Where are you boys from?”

“Bayport,” Frank told him.

The pilot was surprised.

“Why, that’s where I’m bound for.”

“I guess you won’t get there to-night,” said Joe pessimistically.

“I’ve got to get there to-night. I’m carrying the air mail, and it must get through somehow.” The pilot looked at Ducroy’s plane. “I wonder if this old crate will make it.”

“It was running fairly smoothly to-night,” said Frank eagerly. “Do you think you could take off and reach Bayport to-night?”

“Why not? Here, take those mail bags and put them in the plane. We’ll make a try at it, anyway.”

While Frank stowed away the mail bags, Joe showed the pilot the wire connections he had broken in order to prevent Ducroy from getting into the air.

The pilot laughed. “Pretty smart,” he said approvingly. “Even if you hadn’t succeeded in holding them up, they wouldn’t have got very far.”

He quickly repaired the broken connection.

“Now,” he said, “I don’t see any reason why we shouldn’t be able to take off from here and reach Bayport in good time to-night. And won’t my chief’s eyes pop out when I tell him the story of this trip!”

Frank ran around to the front of the plane and gave the propeller a flip. The motor began its clamor again and the pilot waved his arm joyously.

“Climb in!” he shouted. “We’re away!”

The Hardy boys lost no time “climbing in,” and while the curious villagers scattered in all directions, the pilot “gave her the gun” and the plane began to move slowly off across the field. Although it was a cloudy night, the pilot had some instinct which told him the right direction, and he brought the plane off the ground just in time to avoid a fence that seemed to rise suddenly before them. He cleared the fence, cleared the telephone wire beyond the road, just skimmed over the tops of some trees, and then climbed swiftly beyond the danger level.

The boys enjoyed this ride considerably more than they had enjoyed their flights in the tail of the plane. The cold air stung their faces. They found goggles and flying helmets in the seats, and when they donned them they were more comfortable.

Lights of the village flashed far beneath them, and as the plane rose higher in the air they saw lights in the darkness many miles on all sides. Far to the north they could see a dull haze of lights from a distant city. Over to one side they could see a speeding beam of light followed by a little string of twinkling stars, which they identified as a train, racing across the countryside.

The plane roared on swiftly and the thrill of that night flight was sufficient reward to the Hardy boys for all the discomforts they had undergone. They were riding high above the world, which seemed to have disappeared altogether save for the twinkling beams and blobs of light scattered over its black surface.

They saw the pilot gesture. He was pointing ahead.

The Hardy boys could see a widening pencil of light which cut through the blackness of the night. It was the beacon light of the Bayport air field, still many miles ahead, but visible from their great height. Beyond that they could see the twinkling flash of a lighthouse at the mouth of Barmet Bay.

In due time the lights of Bayport came into view, a yellow glow, and to the west they could see the airport, clearly illuminated, a huge glowing rectangle.

The pilot juggled with the controls. The nose of the plane tilted downward. The machine dived in a breathless rush.

Then it banked, and the plane circled the airport, dropping steadily downward as though descending an invisible spiral. The flying field seemed to rise up to meet them. The hangars, the other planes, the tiny figures of men on the field, all became visible. There seemed to be an unusually large number of people about, and the pilot turned and shouted something to the boys, but they could not distinguish what he said, because of the roar of the engine.

Finally the plane straightened out, then glided swiftly down toward the field. It struck the ground with a shock, then bounced and bounded on toward the hangars.

There was a big crowd at the airport. People were running down the field toward the plane. By the time the pilot cut off his engine, by the time the propeller stopped turning and the plane came to a stop, a mob had surrounded the machine.

Frank and Joe looked wonderingly at one another.

“Looks like a reception committee!” said the pilot. “The sheriff must have telephoned to Bayport about his prisoners.”

The Hardy boys stood up. They heard shouts:

“There they are!”

“That’s them!”

“Turn around a little—let’s get a picture!”

The Hardy boys and the pilot had a confused impression of half a dozen cameras leveled at them. Flashlight powder began to explode until the whole scene was as bright as day. An enterprising reporter scrambled up over the side of the plane.

“Interview!” he clamored. “Give me the story, boys! What happened?”

The pilot brushed him aside.

“You boys will have your story in a minute,” he promised. “If you’ll all come up to the office we’ll tell you the whole yarn.”

Chief Collig, at the head of a detail of officers, appeared just then and managed to get the crowd under control, so that the pilot and the Hardy boys were able to get out of the plane. Several airport officials ran up. The pilot saluted.

“Had a forced landing near Jasonville, sir,” he reported to one of these officials, an elderly man. “The mail is safe.”

“Good work, Benton,” said the other. “Come up to the office and tell us what happened. We’ve been mighty curious for the past half hour, since we heard about this hold-up.”

The Hardy boys never forgot the short journey to the office building of the airport. It had all the aspect of a triumphal procession. Scores of people had invaded the flying field, and the police were kept busy keeping the crowds back. Seemingly, the news of the hold-up had spread quickly in Bayport and the flying field suddenly became the Mecca of everyone who could make his way to the airport.

In the office, surrounded by reporters, photographers, police officers, and airport officials, Benton, the pilot, briefly told his story of the hold-up.

“As you know,” he said, “the mail to-night was especially valuable. Cash for a number of payrolls was being sent to one of the Bayport banks from its head office in New York. Somehow, these men must have got wind of it, so they flew out to meet me, tossed a tangle of ropes down on my propeller shaft, then held me up when I crashed. They were just clearing out with the mail bags when these boys appeared on the scene and turned the tables. If it hadn’t been for them, the rascals would have made a clean getaway. Their story is much more interesting than mine.”

Frank and Joe Hardy were then asked to tell the story of their adventures. While the newspapermen scribbled hastily and made frequent dashes to the telephones to inform their city editors of the facts, the boys quietly told how they had decided to follow Ollie Jacobs, how they had learned of the purchase of the airplane, and how they had concealed themselves in the machine and accompanied the rascals in their journeys about the countryside. When they had finished, a veteran post office inspector stepped forward and shook hands with them.

“I hardly need say that your good work will be recognized by the department,” he said. “Your persistence and courage certainly averted a serious robbery, and I am going to recommend that you be suitably rewarded.”

“The only reward we want,” returned Frank, “is to be cleared of the charges against us. You know, we’re out on bail on a charge of robbing the mail several days ago.”

“Why, didn’t you know that you were cleared of that?” exclaimed the inspector. “Your father, Fenton Hardy, came to the airport to-night, shortly before the news of the hold-up was reported, and arrested two mechanics. It seems they had been in touch with Ducroy and his companions by telephone, tipping them off to the time this money shipment was expected. When your father took them away they confessed that they had helped Ducroy manage the other two thefts here, and that Ducroy had deliberately planted evidence against you boys.”

“Charges against them have been withdrawn,” broke in Chief Collig abruptly. “The Hardy boys have been cleared of all suspicion. So far as I’m concerned, I never believed them guilty in the first place.”

The Hardy boys had cleared up the great airport mystery, which had been a nine days’ wonder in Bayport.

Newspapers carried many columns describing the adventures of the boys in trailing the airmail thieves and the entire city united in praising them for their good work. But the boys felt that no praise could equal the delight they felt when they knew they had been cleared of the unjust charges that had been laid against them.

“I knew it! I knew it all along!” declared Hurd Applegate, as he sat in Fenton Hardy’s study the next morning. “It was absolutely ridiculous to arrest them in the first place. Wasn’t it, Elroy?”

Elroy Jefferson, who had come to the Hardy home with Mr. Applegate, nodded affirmatively.

“Quite ridiculous,” he agreed. “I am indeed glad that the whole affair has been cleared up so thoroughly. The boys have been vindicated, the air mail has been saved, and the rascals are in jail. Excellent.”

“When I arrested those two confederates at the airport last night,” said Fenton Hardy, “it didn’t take long to get the whole story out of them. They saw that the game was up. They told me that Ducroy had engineered the whole business. As for planting the evidence against the boys, he got Newt Pipps to steal a sweater and a knife from the garage and he left those near the scene to incriminate Frank.”

“How about the footprints?” asked Joe. “How did he manage that?”

“He noticed that you were wearing the new shoes, so he got a similar pair, of the same size, in another town. After all, you can hardly blame the police, with all that evidence, particularly when you had no alibi.”

“The reason we couldn’t explain our alibi,” said Frank, “was because we had been out to a cabin in Beach Grove that afternoon looking for evidence against Ducroy and the others. We thought we’d keep quiet about that until we learned a little more about them.”

“You took a great many chances,” said Mr. Hardy gravely. “If I had known you were flying around the country in the tail of an airplane operated by three mail robbers, I wouldn’t have been very easy in my mind.”

“Now, Fenton, don’t start worrying about that now,” advised Elroy Jefferson. “The boys have done excellent work and they’ve come through it quite safe and sound, which is all that matters.”

“We want to thank you and Mr. Applegate for going bail for us,” said Joe. “If you hadn’t put up the money we would have had to stay in jail and the mail robbers would probably be at large yet.”

“Don’t thank us,” snapped Hurd Applegate. “We didn’t risk any money. We knew you were innocent. I think I’m sufficient judge of character to know a crook when I see one.”

The boys soon would need to know this to learn “What Happened at Midnight.”

“The bail money was returned to us this morning,” said Elroy Jefferson. “The police were quite apologetic.”

“The postal department has been apologetic too,” said Fenton Hardy. “As you remember, when the boys were arrested they relieved me of my assignment to work on the case, so that when I went out to the airport last night, following up the information the boys had sent on here by telephone while I was away, I was really exceeding my authority. However, the post office people now admit they were mistaken and have asked me to hold myself in readiness to accept other cases if they should arise.”

“Excellent! Excellent!” said Hurd Applegate. “Everything has turned out wonderfully for all concerned.”

“Except for Giles Ducroy and his gang,” remarked Frank.

“Too bad about them!” growled Hurd. “They’re safely locked up in jail, where they belong. Serves ’em right. Don’t you think so, Elroy?”

“Absolutely!” agreed Elroy Jefferson. “It is a fitting end to the great airport mystery.”

THE END

TRANSCRIBER NOTES

Misspelled words and printer errors have been corrected. Where multiple spellings occur, majority use has been employed.

Punctuation has been maintained except where obvious printer errors occur.

[The end of The Great Airport Mystery by Franklin W. Dixon (Stratemeyer pseudonym)]