The silence around the camp-fire was profound and reflective, but there was some squirming and surreptitious examination of caps and flints. The questioning call of the hoot owl was answered by a weird, uncanny, succession of sharp barks growing closer and faster, ending in a mournful, high-pitched, long-drawn, quavering howl. The noisy activity of the encampment became momentarily slowed and then went on again. The first guard came off duty with an apparent sense of relief and grew very loquacious. One of them joined the silent circle of tenderfeet around the blazing fire. "Phew!" he grunted as he sat down. "Hear those calls?" His question remained unanswered, but he did not seem surprised. "When you go on, Doc?" he asked. "One o'clock," answered Dr. Whiting. He looked around pityingly. "Calls?" he sneered. "Don't you know an owl or a wolf when you hear one?" There was a lack of sincerity in his voice which could not be disguised. The doctor was like the boy who whistled when going through the woods. Midnight came and went, and half an hour later the corporal of the next watch rooted out his men and led them off to relieve the present guard. He cautioned them again against standing up. "To a Injun's eyes a man standin' up on th' prairie is as plain as Chimbly Rock," he asserted. "Besides, ye kin see a hull lot better if yer eyes air clost ter th' ground, lookin' agin' th' horizon. Don't git narvous, an' don't throw th' camp inter a scare about nothin'." An hour later an owl hooted very close to Dr. Whiting and he sprang to his feet. As he did so he heard the remarkably well imitated twang of a bowstring, and his imagination supplied his own interpretation to the sound passing his ear. Before he could collect his panic-stricken senses he was seized from behind and a moment later, bound with rawhide and gagged with buckskin, he lay on his back. A rough hand seized his hair at the same instant that something cold touched his scalp. At that moment his attacker sneezed, and a rough, tense voice growled a challenge from the darkness behind him. "Who's thar?" called Tom Boyd, the clicking of his rifle hammers sharp and ominous. The hand clutching the doctor's hair released it and the action was followed by a soft and hurried movement through the woods. "Who's thar?" came the low growl again, as Tom crept into the bound man's range of vision and peered into the blackness of the woods. Waiting a moment, the plainsman muttered something about being mistaken, and departed silently. After an agony of suspense, the bound man heard the approach of another figure, and soon the corporal of his guard stopped near him and swore vengefully under his breath as his soft query brought no answer.