And if it was a human voice it must of necessity be an enemy voice, for no friend of his or of Uncle Sam's could be in that place at that hour on a legitimate errand. A moment later he detected another voice in a different key yet pitched hardly above a whisper. So it was a conference! A conference of whom and about what? He crept still farther forward. Right before him stretched a little glade full of small trees and undergrowth with a scarcely visible path leading downward. To press too far between the bushes would have inevitably betrayed him. He halted with his rifle ready for action and listened. The conversation seemed to be an earnest one and in their earnestness the conferees at times forgot caution, for, as one of the men raised his voice in expostulation, Frank could note that he was talking German. But it was not that which made him start suddenly and clutch his rifle more tightly. He had heard that voice before. Where and when? He cudgeled his brain and then it came to him. It was Nick Rabig's voice! That is, he thought it was. But at that distance he could not be perfectly sure. At any rate it was time to act. With a bound he leaped forward. "Halt!" he cried. "Halt or I fire." There were startled exclamations from both men, and then a prodigious scrambling in the bushes as they tried to escape. Bang! went Frank's rifle, and there was a scream followed by a heavy fall. Frank rushed forward, but caught his foot in a tangled root and fell. His gun flew from his hand and his head came in contact with a stump. The jagged edges cut a gash in his forehead, and for a moment he was utterly dazed. He strove desperately to retain his senses and in a minute or two his brain ceased to whirl. He staggered drunkenly to his rifle and picked it up. And at this moment there was a sound of hurrying feet, and Wilson, the corporal of the guard, came running up, accompanied by Fred Anderson who had been on duty near by. "What is it, Sheldon?" asked the corporal "What were you shooting at?" Frank tried to speak, but his tongue was thick and the words would not come." "He's wounded!" exclaimed Anderson, as he saw with alarm the blood flowing freely from Frank's forehead. They deftly bound up his head, and by this time Frank had found his voice. "It's nothing," he managed to say. "I fell and cut my head. It's only a scratch. I heard two men talking German here in the bushes and I started in to get them. They wouldn't stop when I ordered them to, and I fired, I don't know whether I got them or not." "We'll see," said the corporal, and led the way into the bushes while Frank and Fred followed close on his heels. From one side to the other the corporal flashed his light, and before long he uttered an exclamation.