"Tom, do you think that spy left behind by my cousin could have learned in any way about our plan?"

They were passing over a section of Northern France, keeping a mile and more above the surface of the earth, when Jack called out in this fashion. Talking is never easy aboard a working plane. The splutter of the motor, added to the noise caused by the spinning propellers, as well as the fact that as a rule pilot and observer keep well muffled up because of the chill in the rarified air, all combine to make it difficult.

But Jack was hard to repress. Especially just then did he feel as if he must find some answer to certain doubts which were beginning to oppress him.

"There's no way of telling," Tom answered promptly. "We've already seen that the fellow is a clever, as well as desperate, rascal. He may be an American, though I'm rather inclined to believe your cousin has found a native better suited to his needs. And such a treacherous Frenchman would prove a tricky and slippery sort. Yes, he may have overheard us say something that would put him wise to our big game."

"I hope not, I surely do," Jack continued, looking serious again. "Fact is, Tom, I'll never feel easy until we see the ocean under us."

At that Tom laughed heartily. He even put a little extra vim into his merriment in the hope of raising his chum's drooping spirits.

"That sounds mighty close to a joke, Jack, for a fact," he said.

"I'd like to know how you make that out?" demanded the other.

"Why, most people would be apt to say our troubles were likely to begin when we have cut loose from the land and see nothing below us as far as the eye can reach but the blue water of the Atlantic."

"All right," cried Jack, showing no sign of changing his mind. "I'll willingly take chances with nature rather than the perfidy and treachery of mankind. Somehow, I can't believe that we're really launched on the journey."

"Wake up then, old fellow, and shake yourself. You'll find we've made a pretty fair start. Already we've put thirty miles behind us. Unless we run up against some snag, and have engine trouble, we ought to get to the Channel long before dark sets in."

So Jack relapsed into silence for a time. As he was not needed in order to run the motor or guide the plane in its progress westward, Jack could amuse himself in using the powerful binoculars.

They were at the time far removed from the earth, but through the wonderful lenses of the glasses objects became fairly distinct. So Jack could see much to interest him as they sped onward. Finally he again broke out with an exclamation.

"Nothing but the ruins of towns and villages down below, Tom," he called.
"The fighting has been fierce along this sector, I should say. Why, even
the woods have been smashed, and it looks like a regular desert. Poor
France, what you must have suffered at the hands of those savage Huns."

"Yes," replied the pilot, over his shoulder, "here is where much of the most desperate fighting of the British took place. Some of those ruined places were beautiful French towns only a few years ago, where laces and such things were made for most of the fashionable world. Now they look about like the ruins of Ninevah or Babylon."

Fortune favored them during the next hour, and even Jack's spirits had begun to improve. Then came a check to the sanguine nature of the outlook.

"Sorry to tell you, Jack," reported Tom, after some uneasy movements, which the other had noticed with growing alarm, "that we'll have to make a landing. After all, it's not going to be a non-stop flight to the coast. Only a little matter, but it should be looked after before it develops into serious trouble. I'm going to drop down to a lower level, where we can keep an eye out for a proper landing place."

"But that means time lost!"

"We can spare an hour if necessary, and still get to Dunkirk by evening," Tom replied cheerfully. "I was a bit suspicious of that very thing, and only for our desperate need of haste would have waited to start until it had been gone over again. But then I took chances, knowing it would, at the worst, mean only a stop for repairs. Sorry, but it can't be helped."

When the plane had reached a distance of a thousand feet above the earth, with Jack eagerly looking for a favorable landing place, the latter had managed to recover from his depression.

"I see what looks like a fine stretch, Tom," he now announced. "Notice that road looking as if it might be pitted with shell-holes? Just on its right, where that single tree trunk stands, there's a field as level as a barn floor. Circle around, and let's get closer to it."

Further examination convinced them that they had really run upon a suitable landing place. What pleased Tom still more was the fact that so far there had been no evidence of human presence near by.

This meant that they would not be bothered during the time required for overhauling the engine by curious spectators, who might even question their right to be flying away from the front.

The landing was made in good style, and with only a few bumps, thanks to the smooth character of the field's surface. Even Jack was compelled to admit that though they had met with trouble, matters might be much worse.

"We'll get busy now, and soon have things as fit as a fiddle," said Tom, throwing off some of his superfluous garments so as to be free to work.

By this time both boys had grown to be real experts in all sorts of mechanical repairing, as every airman must of necessity become before he can pass the acid test. Unlike the driver of a car on country roads, when a break-down occurs he cannot step to a neighboring house, use the long distance or local telephone, and summon help. The airman is usually compelled to depend exclusively on his own ability to overcome the difficulty.

To get at the seat of trouble necessitated considerable disarrangement of the motor's parts. This consumed more or less time, and the minutes passing were jealously given up by the impatient Jack.

But the boys worked fast, and finally all had been accomplished. Tom tested the engine, and pronounced himself satisfied, while Jack looked over the field ahead of them.

"It's going to take us to Dunkirk without any further trouble, I give you my word for it, Jack," he said. "How long have we been here?"

"Just one hour, lacking three minutes," came the prompt reply.

"Then I'm safe," laughed Tom; "for I said within the hour. Come, pile aboard and we'll be off. Sure you examined the ground ahead, and saw to it we'd hit no bumps that might give us trouble?"

"It's all right there, Tom; could hardly be better. But be sure you don't change from a straight course, because there's a nasty shell-hole, about ten feet deep, to the left. If we struck that—good-night!"

"I notice you marked it with that pole, Jack, and I'll swing clear, you can depend on that."

They had no difficulty in making a successful ascent. Once free from the ground, the plane's nose was again turned toward the southwest. Tom had long before marked out his course, and kept an eye on the compass as well as on his little chart.

He knew they were heading for the Channel port as straight as the crow flies. The sun was getting far down in the western sky, and it was now necessary to shield their eyes when looking ahead, on account of the dazzling glare that at times threatened to blind them.

The character of the country below had changed materially, Jack told the pilot, who seldom had a chance to look through the glasses, since his entire attention was taken up with manipulating the engine, watching its rhythmical working, and keeping the plane pushing directly on its course.

"Heine didn't get a chance to ruin things here when he passed through, going to Paris and to his smash on the Marne," Jack explained. "Towns and villages look natural, as I see them, and they must have harvested crops in those brown fields. This is a bit of the real France, and entirely different from the horrible desert we've been at work in so long."

The afternoon was wearing away. Jack frequently stared eagerly off to the west, when the sun's glowing face was veiled for a brief time by some friendly cloud. Several times he believed he could see something that looked like a stretch of water, but dared not voice his hopes.

Then came a time when a heavier cloud than usual masked the brightness of the declining sun. Another long earnest look and Jack burst out with a triumphant shout.

"Tom, I can see the Channel, as sure as you're born!" was the burden of his announcement; and of course this caused the pilot to demand that he too be given a chance to glimpse the doubly welcome sight.

There could not be any mistake about it. Tom corroborated what Jack had declared. It was undoubtedly the English Channel they saw, showing that their journey from the American front had been successfully accomplished.

"Now for Dunkirk!" jubilantly cried Jack, looking as though he had thrown off the weight of dull care, and was once more light-hearted. "And by the same token, Tom, unless I miss my guess, that may be the city we're heading for over yonder a little further to the south."

"Then I kept my course fairly well, you'll admit," the pilot shouted at him, naturally feeling conscious of a little pride over his achievement.

Rapidly they pushed on with a slight change of course. Jack kept using the glasses and reported his observations to the busily engaged pilot.

"It'll be dusk, likely, when we land," he observed at one time. "But that doesn't cut much figure, for we can easily find our way down to Beverly's hangar on the coast. He said it was only a few miles from town, and they'll know at the aviation field, of course."

"He gave us the name of a British officer who would post us," added Tom.

After a bit they were passing over the outskirts of Dunkirk, and making for what appeared to be an aviation field, since they could see various hangars, and another plane was just settling ahead of them.

Ten minutes passed, and Jack was delighted to find that they had made a successful landing. A number of French and British aviation men hastened to surround them, more than curious to know what strange chance had brought two Yankee fliers to Dunkirk.

Of course neither Tom nor Jack meant to afford them the least satisfaction. They had certain business to transact, and after that was off their hands the great adventure loomed beyond.

Accordingly, their first act was to find the man to whom they had been referred by Lieutenant Beverly.

"We want to see Major Denning; can anybody direct us to him?" Tom asked.

"That happens to be my name," remarked a red-faced officer on the outskirts of the crowd and who had just arrived. "What can I do for you?"

"Lieutenant Colin Beverly of the American aviation corps referred us to you, Major," said Tom. "We have a message for you, after which we must deliver an official packet sent by our general to the command here and make arrangements to have our plane sent back to where we started from some hours ago, on the American fighting front."

"I shall be pleased to give you any assistance in my power, gentlemen," said the British major, being apparently a very agreeable and accommodating man indeed, as Beverly had informed them they would find him.

Stepping away from the crowd the Air Service Boys delivered their message, which was really a sort of prearranged password.

"Lieutenant Beverly is a cousin of mine, you know; which makes me more than anxious concerning him just now," went on Major Denning, after these formalities had been gone through with.

"Why so, Major?" demanded Tom, while Jack looked worried.

Whereupon the red-faced major drew them still further to one side, and, lowering his heavy voice so as not to be overheard by others, went on to say:

"I, as you know, know something about that wonderful big bomber he's had sent over, and how he means to give Berlin a scare shortly. I've even had the privilege of looking the monster over, and feeling a thrill at picturing how it would give the Huns a fright when it appeared over Berlin. But you see its presence here is a secret, and known to but few of us."

"Glad to hear it, Major," Tom remarked. "But please explain why you are worried about Beverly."

"That is," continued the officer, "because an explosion was heard, coming from the south, just a short time ago. Everybody believes it must be the airdrome sheltering the dirigible Britain sent over here for use, and which lies further down the coast. But, much as I hate to say it, I fear something serious has happened to Beverly's hangar; in fact that a bomb has destroyed it, or else some rank Hun treachery has been at work there!"