Suddenly there came a shout. A moment later the two German aviators who were delaying the departure burst into sight at a dead run. "Quick!" called one. "We are discovered!" Immediately the others--Frank and Jack among them--leaped into their machines and soared into the air. The last comers also leaped for their craft and succeeded in getting above ground just as rifles began to crack in the French camp. Came a sudden cry from the machine nearest that of Frank and Jack. The lads saw a man rise to his feet, throw up his arms and pitch, head foremost, toward the ground. The aircraft, freed of a guiding hand, rocked a moment crazily and then turned over, hurling its other occupant into space. There was a cry of anger from aboard some of the other German craft, but no man raised a hand to stay the flight of his car. It would have been suicide and the Germans realized it. They sped away into the darkness whence they had come. Frank and Jack, in their British hydroplane, went with them. For an hour or two the aeroplanes sped through the darkness at undiminished speed; then the foremost craft slowed down. The others did likewise. "Surely we haven't reached the German lines already?" said Jack. Frank shrugged his shoulders. "You know about as much of what is going on as I do," he returned. "Evidently we are going down, however." The lad was right. The leading German plane swooped toward the earth and the others followed its example. A few minutes later all had reached the ground safely and their occupants had alighted. The two lads glanced around. It was very dark. A short distance to the north they could see the broad expanse of the North Sea, stretching away in the night. The dark waves lapped the shore gently with a faint thrashing sound. The water was very calm. Except for the figures that had alighted upon the shore in the darkness there was not a human being in sight. To the south, to the east and west stretched miles and miles of sand dunes. Just these sand dunes and the waters of the North Sea--there was nothing else in sight. At a signal the men gathered around the man who appeared to be the leader. Frank and Jack thanked their lucky stars that the night was very dark, for otherwise they would have been in imminent danger of being discovered; and each lad realized that it would go hard with them should their true identities be penetrated. The darkness served them like a shield. Nevertheless, both lads kept their hands on their revolvers. Each had determined that if discovered, he would make an effort to escape in the nearest of the aircraft. Each knew that there was little hope of such an escape, but, realizing what was in store for them should they be discovered and captured, they had decided it would be better to die fighting than to be stood up against a wall and shot, or, possibly, hanged. The group of men on the bench became silent as the leader addressed them.