The fire he had started blazed up at once, owing to the petrol. And at once a thick, acrid smoke filled the place. He was well up on the stairs, and thus safe from being choked. But he was in danger should the Germans come down, though even so, since the steps were wide, there was a chance for him. But he did not expect them to come down. He thought the smoke would drive them out, since as nearly as he could judge his fire was directly under the room in which the most of the commotion upstairs was taking place.
It was not long before he heard coughing upstairs, the first sign that the smoke was doing its work. By that time a brisk fire was burning. It had run up the posts to the beams that formed the chief support of the room above, and to his delight Frank saw that these burned far more fiercely and quickly than he had hoped. Plainly the wood was old and dry.
Above, as the fire spread, louder cries succeeded the coughing. And then came the crucial test by which his daring experiment had to stand or fall. Some one opened the door at the head of the stairs. Now, if ever, he was to be discovered! But as the door was opened the smoke was drawn up, and the German who had come to it jumped back.
"The whole place is burning! Get out!" he cried, in German. "There may be explosive spirits still down there!"
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.