He slammed the door shut, and Frank heard running footsteps above. He waited until there were no more, and then, almost overcome by the smoke, slipped through the door. No one was left in the hallway into which he came. The place was full of smoke. He did not venture to the front door by which he had entered, but, still dragging his can of petrol, went to the back. Going through the kitchen, he found another door, as he had been sure he would and in a moment he was drinking in the cool, fresh air. The rain that was beating down on him now was welcome.

Just as he reached the open there was a sharp explosion behind him, and he looked back, to see the windows on the ground floor glowing. That was the other can of petrol, as he could guess readily enough. At once he ducked, and, running low, got well to one side of the house. Then, just as a great burst of flame lighted up the whole scene, he dropped to the ground, and lay peering toward the road in front of the inn.

A dozen officers and as many men, all in the German uniform, with the spiked helmets that made them so unmistakable, were in the road, staring at the burning house. And it was not until Frank saw how angry one of the officers was that he realized what a useful idea his had really been. Now detection of the Germans was certain. Investigation was almost certain to be made of a fire in a building so far out of the range of the German artillery as this. And so, even if neither he nor Captain Greene got back in time, the torch he had lighted, meaning only to secure his own escape, was likely to prove a death blow to the German hopes of secrecy.

Frank could not hear what the Germans were saying, but he had no intention of getting closer in an attempt to do so. Instead, having satisfied himself that there were no pickets behind the burning inn, he began crawling cautiously to the rear. It was a difficult task, especially so because of the petrol, which was no light burden. But he managed to get well out of the lighted zone and then he decided that it would be safe to straighten up and walk along.

As he went along the burning building served him well. It gave him a fixed landmark from which he could lay his course to the spot where he had left the monoplane and Captain Greene. By looking back from time to time he could correct his course, when he was crossing fields. And so without the guidance of roads, and partly to make better time and partly to avoid stray German pickets, he chose to stay away almost entirely from the roads and go across country.

From the fields in which they had descended to the inn the distance, as nearly as he had been able to guess it, was about a mile. He shortened this somewhat on the return trip. And he was within a quarter of a mile of the meeting place when he became suddenly conscious of something that was not just right. At first he was tempted to stop, but he overcame the temptation. The thing that had warned him of a possible danger was a trifling noise, yet one that was out of the ordinary. What the noise was he could scarcely have told. Perhaps the breaking of a twig, perhaps the slipping of a foot along a suddenly encountered patch of mud. At any rate he was sure that he had been followed.

He slowed down and now he could hear, or thought he could, the heavy breathing of at least two men. He was not certain of this; he was willing to admit to himself that he might be fancying it.

"If they're after me, why don't they take me?" he wondered to himself.

But the explanation came to him almost as soon as he had asked himself the question. Whoever was following him could reason from the sight of the can of petrol he was carrying that he was going to some definite place where that petrol was wanted. And it would require no great stretch of the imagination for his trailers to decide that he must be carrying fuel to the aeroplane that had worked such havoc with the German plans.

"They think I'll lead them to the 'plane," he thought. Half a dozen plans for misleading them came to him. But none seemed practicable.

Frank was intensely dogged in his determination to accomplish anything he had set out to do. The idea of giving up now, even to mislead his pursuers and so save Captain Greene from capture, was repugnant to him.

He wanted to foil the men behind him--unless, as was possible, he only imagined that they were behind him--and still do what he had set out to do, which was in this instance to refill that empty petrol tank on the monoplane.

It was the purely accidental movement of putting his hand into his pocket to dry it off that gave him the idea. It met the pocket flashlight Captain Greene had given him, and at once he remembered a use for it of which the aviator had told him. To follow the plan did not mean that it would succeed, but it represented a chance, anyhow. And so when he came to the fence which he remembered climbing on his way from the monoplane, he stopped on the top rail, having pushed his can of petrol through first. In the field now immediately in front of him, but far away still, on the other side of the field, lay the monoplane. He could not see it in the driving rain but he knew that it was there.

There too would be Greene, waiting for him, and in all probability at this moment straining his eyes watching for his return. On that depended his chance of success in the plan that had come to him. On that, and on Greene's presence of mind and quick-wittedness.

So, still astride of the top rail, he began signalling with his pocket flashlight. He spelled out his message in Morse code, using a long pressure of the releasing switch for the dash and a short one for the dot. Word by word he spelled out his message, telling that he suspected that at least two Germans were trailing him. And at the end he signalled a request that if he had understood, Greene should wait a half minute and then imitate an owl's cry. He chose an owl because he had heard one or two earlier in the night. And he added that if he got the signal he would keep on heading for the monoplane. He suggested nothing to Greene; the rest was decidedly up to the aviator. Frank had done his share.

If there were Germans actually within sight of him, they did not attempt to interfere with him while he was flashing his message. But he had reckoned confidently that they would not. He was sure that he had not betrayed the fact that he knew he was being followed, and they would naturally suppose that this stop for signalling was part of a pre-arranged plan. He now dropped to the ground, picked up his can and took two or three quick steps. Then he stopped abruptly and was sure that he heard a footstep behind him. He grinned to himself, and just then the hoot of an owl sounded. Then he went on.

"I'll make it easier for them," he said. "Perhaps they wouldn't like to follow me right across the field!"

So he skirted the fence and the hedge at the side, and went around three sides of the field to reach the monoplane. And, as soon as it was in sight, all his suspicions were verified, for from behind there came a sharp exclamation in German, and he was told to stop, just as a heavy hand gripped his shoulder.

"Ja, we were right!" exclaimed one man in German. "There is their aeroplane! Now for the other--"

He never finished the sentence. Instead, he threw up his hands and pitched forward, just as a revolver cracked sharply in the silent night.

With an oath the man who held Frank threw him aside, at the same moment shooting in the direction of the flash of Greene's pistol. But the Englishman's revolver spoke at the same moment, and he too fell. Frank's ruse had saved the day!

CHAPTER XIV

MENTIONED IN DISPATCHES!

"Keep back!" called Greene sharply to Frank.

His revolver still in his hand, he flashed the powerful light Frank had used in the monoplane into the faces of the two Germans. They lay groaning within a foot or two of one another.

"No tricks!" said Greene, sharply. "I don't want to finish you, but I'll shoot again if you make a move, except you can throw away your revolvers."

He spoke in German, and both of the wounded men obeyed. Frank was immensely relieved. He had been afraid that they had been killed, and the thought had sickened him. He realized fully that it would have been in accordance with the idea of war had Greene killed them both; that it would have been no more than his duty. And yet he was more than glad that they were alive and, so far as he could judge at that moment, not badly hurt or not dangerously wounded, at least.

"Fill that tank with the petrol," said Greene to Frank, "but leave a little in the can."

Frank obeyed, wondering why the order was given. Then Greene pushed the monoplane along the ground for some distance until it was in a favorable position to take the air.

"All right! Get in!" he said. "Strap yourself in. Know how the straps go? Right! I'm going to make a bonfire. It'll bring someone to help those poor chaps. I don't want them to have to lie here all night unless they have to."

He took the can which Frank had almost emptied and poured what gasoline remained on the ground that had been protected from the rain by one wing of the monoplane. Then he flung a match into the now highly inflammable stubble, and a flame leaped up at once, lighting the monoplane and the two wounded Germans. In a moment more he was in his place and the monoplane was plunging along the ground. Then it took the air and rose swiftly to a safe height. And then for the first time there was a chance for explanations.

"By Jove, how did you come to think of flashing that message to me?"

cried Greene. "That was an idea! I almost gave it all away by answering before I realized what you were telling me. What was that fire I saw?

Looked to me like the very place you said you were going to."

So Frank explained.

"Oh, splendid--my word, splendid!" cried Greene. "I fancy we'll find they've started this way already. Hullo--yes, by Jove, there come some of our fellows now! See, over there to the right? Aeroplanes--gone to spot those Johnnies. They didn't wait for us to come back!"

He dropped to a bare hundred feet of elevation now and in a moment Frank could see why. Below them a ma.s.s of cavalry was in motion.

"There they go!" cried Greene. "Your beacon gave them the line. The general must have decided that was confirmation enough."

Now came a shouting from below, and Greene answered it by swooping down to a landing in the field. An officer put his horse to the wall and rode up beside them.

"Captain Greene, by any chance?" he called, peering at them.

"Yes, colonel," said Greene, saluting. "The Germans are in a clump of woods on the Amiens road. In an angle of that road and the one from LaFere, rather. I don't know the exact strength, but have reason to believe about five thousand."

"There's no doubt about their being there, though?"

"None at all, sir. They shot a hole in my tank, and I had to wait to get enough essence to come back. All mine leaked before I could make a landing to plug the bullet hole. Did you start on the sight of that burning house?"

"Yes. The staff couldn't see why a house should be burning unless there were Germans about. Very well. Report back to headquarters, captain.

They're waiting for you."

"Very well, sir."

"I thought so," he said to Frank, when they were in the air again.

"You'll hear more of this night's work before you've done, my boy.

There's a deal of grat.i.tude due you. But I'd like to know what those Dutchmen were up to!"

Five minutes more saw them landed safely at headquarters, and it was only a few moments before they were in the presence of General Smith-Derrien. He listened to Greene's brief report in silence.

"There is more to be told of what my pa.s.senger and observer did, sir,"

he added, when he had sketched the essential facts. "I will make a written report of that direct to you."

"Do so," said the general. "You have done very well. Had it not been for the information we have obtained in this way, the whole headquarters staff might have been captured. The Germans evidently learned, through spies, of the orders that had been issued for continuing the retirement, and had slipped this force through to intercept the staff. I have been able to turn the tables on them, however. They will have trouble, I think, in escaping the forces sent against them."