They were not even challenged as they sped through the camp, turning this way and that, and they had passed beyond the last row of tents before a hubbub from the rear told them that their flight had been discovered. "We must be careful," cried Hal, as he rode his wheel close beside Chester. "There is still the outpost to pass." But they did not diminish their speed. Rather, if anything, they pedaled faster; and then the outpost came into sight--a long line of men, almost in front of them. Some were pacing to and fro, while others sat upon the ground. The riders were upon them before they knew it, and two flying bicycles sped between the German troopers. A cry of "halt!" went unheeded, and the Germans, quickly bringing their rifles to their shoulders, sent a volley after the lads. But neither was hit. In the darkness the Germans were unable to aim carefully. The boys heard the hum of bullets around them, but they did not falter. There was no second volley, for the lads had disappeared in the darkness, and the Germans were not minded to spend their ammunition foolishly. The first streak of dawn appeared in the sky, and still the boys rode on swiftly. But at length Hal slowed down and Chester followed suit. "I'm tired out," said Hal, as he jumped from his bicycle. "And so am I," replied Chester, as he, too, jumped to the ground to stretch his legs. Suddenly from the distance in which they had come came a faint "chug-chug." Chester pricked up his ears. "What's that?" he demanded anxiously. For a brief moment Hal paused to listen. The sound became louder. Hal sprang toward his bicycle. "Come on!" he cried, and leaped into the saddle. "Motorcycles! We are pursued!" Chester was hardly a second behind him, and the two lads were again riding madly along the road. Fortunately there were many curves in the highway, and this fact prevented their pursuers from sighting them from any great distance. Hal suddenly brought his bicycle to an abrupt stop and jumped to the ground. Although not knowing what plan Hal had in his mind, Chester immediately did likewise. The spot where they had alighted was in the midst of a clump of trees, and quickly the lads drew their bicycles in among them, hiding them from sight of the road. Then Hal turned, and, with Chester close behind him, dashed back in the direction from which they had come, taking care to keep well within the shelter of the trees. And now Chester made out the object of his friend's wild dash. It was a farmhouse, setting well back from the road. Chester had not detected it as they sped by, but Hal's keen eyes had singled it out as a possible refuge. "We'll have to take a chance of the occupants being friendly," Hal told his friend, as they ran toward the house. "If they will allow us to hide here until night, we may be able to get back to our lines safely."