Then it starts in a bee-line for its loft, whether that is five miles away or hundreds of miles. Some peculiar instinct tells it in which way home lies. It seldom if ever goes astray. Sometimes birds have made a thousand miles, and shown up at their home coop days after being set free."

"Well, then, the man who threw it into the air, after fastening this cipher message to it, must be over to the southeast of us," affirmed Jack.

"The bird was released within five minutes or so of the time I fired," Tom told his chum. "It's even possible the spy may have heard the report of my gun."

"Tom, why not try to capture that spy?" asked Jack, eagerly, ready for any sort of excitement.

The young aviators started off, walking briskly. They kept their eyes alertly open as they proceeded. At the same time, on Tom's suggestion, they continued to act as though still looking for game, even investigating at a burrow that certainly was used by rabbits, as the tracks plainly indicated.

Tom never deviated from a direct line due southeast. He knew that their best chance of making a valuable discovery lay in finding the place where the carrier pigeon had been released, to fly across the lines to its home loft. This might be many miles to the rear of the fighting front, even on Lorraine territory, in the neighborhood of the fortified city of Metz itself.

The two passed over a mile without making any sort of discovery, Jack, who did not possess quite as determined a nature as his comrade, was already commencing to make certain sounds akin to complainings, as though he felt keenly disgruntled because of their lack of success.

"Guess we'll have to give it up, Tom," he finally remarked.

"Wait," said Tom. "Before doing that let's investigate that old shattered farmhouse over yonder."

"Hello!" exclaimed Jack, plucking up some fresh interest, "have you located one of those remains of a building, then? I was coming to believe there wasn't so much as a broken wall left standing for a space of five square miles, so complete has been the destruction. But I see what you mean, Tom."

They walked ahead again, and approached the ruined farmhouse. It had been riddled through and through by shot and shell. Three-fourths of the original building lay in piles, the stones heaped up as they had fallen.

"Queer, isn't it, that the kitchen part escaped the smashing fire, and still stands," observed Jack. "I warrant you this is the only part of a building left around here. Tom, would our spy be likely to take up his headquarters in such a place as this, do you think?"

"I don't know," came the answer. "We can soon find out."

"He might feel desperate enough to open fire on us," suggested Jack, though he did not shrink or hold back when Tom advanced; for Jack Parmly did not have a drop of cowardly blood in his veins.

Tom turned and waved his hand as though beckoning to others who might be coming after them. He even called out in his best French, as if there were a dozen back of him, that there was a possibility of securing at least a drink of cold water at the old-fashioned well with a sweep that stood near the kitchen of the ruined farmhouse.

"Good idea, Tom!" commented the other, chuckling with amusement. "If he gets the notion in his head that we are legion he won't be so apt to blaze away at us, knowing it would mean a short shrift for him. He may prefer to play the poor French peasant part, and try to pull the wool over our eyes."

Presently they arrived at the door. It was hanging from one hinge, and the entire place presented a vivid picture of the utter desolation cruel war always brings in its train.

Tom's first act before entering was to look down at the ground just before the door. Some intuition told him that if the place had been recently occupied they would possibly find some evidences of the fact in the earth.

"See there, Jack!" he suddenly exclaimed, as he pointed down close to his feet. "Fresh tracks, and made by a man's shoes in the bargain!"

"Some one has been in here for a fact, Tom, and I wouldn't be afraid to wager he saw us coming and cleared out in a hurry. He could have skirted those bushes, and got clear easy enough. Do you think it could have been the same chap who freed that pigeon?"

"No doubt about it," and Tom, stooping, picked up some small object. "See, here's a feather that was sticking to that dead weed. It's from a bird of the same color as the pigeon, perhaps from the very one I've got in my pocket."

"That settles it," snapped the pleased Jack. "I must say you're a clever hand at finding these things out. I'd have never dreamed of looking down at my feet, but blundered right into the shack to see if—Oh! What do you think of the luck we're in this day, Tom? See what stands there on that poor old three-legged table!"

Jack's excitement was natural, as Tom readily understood when he looked; for there was a small basket or cage made from oziers or willow wands; and inside this they could see two blue gray homing pigeons, mates to the one Tom had shot only a short time before!

CHAPTER III
A SPY BAFFLED

Both young aviators stared at the wicker cage containing the two pigeons. The birds had been still up to then, but now commenced to make cooing sounds, as though pleased at having human company. Apparently they were inclined to be sociable, as Jack afterwards put it.

"So he discovered us coming along," Jack went on to say, "and skipped out in such a hurry he didn't have time to carry away the cage with him."

"He must have climbed out of this window in the side of the wall," observed Tom. "We could have seen him if he had used the door. Yes, there are footprints underneath the window. He ran down behind those bushes and reached the stone wall that leads to the broken country and what is left of the woods."

"The chances are he had all that mapped out beforehand," suggested Jack. "Surely a spy has always to keep a door open for retreat."

"Yes. Why not? They take their lives in their hands every time they enter the hostile lines, and you can't blame a man for wanting to live a little longer, especially if he believes he can serve his country."

"Perhaps he hasn't got such a good start but that we could overtake him if we went after him now," suggested Jack.

"We might take a turn that way," his chum agreed. "But not too far afield. We didn't start out to search for spies, and we've only got a single gun between us. Even my automatic was left behind, because I didn't expect to have any use for it, and get tired carrying the thing, with its belt."

"But these pigeons here, Tom?"

"We can leave them until we get back. That's one reason why I don't want to get out of sight of the place. He might make a round, and carry the birds away while we were engaged in a hunt half a mile off. And it may be of much more importance that those live birds arrive in the French camp than that we should bag the spy."

"I get you, Tom; so let's commence our little man-hunt right away."

The two friends set off. Tom tried to follow the course he believed the spy must have taken on quitting the old farmhouse ruins. That his reckoning was clear he proved several times by pointing out to his companion plain evidences that some other person had passed along the way before them.

Here the marks of shoes could be detected in the soft earth. A little further on, and at a point where the man must have crawled in order to keep from being seen, they found tracks where his toes had dragged