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.