What a thrill passed through Dick's whole frame as his eager hand touched that welcome blade. Its buckhorn handle, too, felt very familiar, and he was almost sure it would turn out to be the hunting-knife Roger valued so highly because of the associations connected with it. As it possessed a keen edge, he found no difficulty in bending down and severing his bonds. After that he stopped and listened, but there was nothing to indicate that his actions had been discovered. The owl had commenced his mournful hooting again; and the tree-frog piped up louder than ever, Dick noticed with considerable satisfaction, for he hoped the sounds would muffle any slight noise he would chance to make. Now he turned to set Roger free. He hoped in his heart that, upon being aroused, Roger would not utter an exclamation. With this possibility in mind Dick very cautiously crept over to the other tree. He could hear Roger's heavy breathing, showing that the boy still slept. With great care Dick raised himself until he could put his lips close to the other's ear, when he whispered: "Roger, wake up, but keep very still! I am going to cut your bonds now!" The boy gave a great start, but fortunately he did not attempt to answer. He comprehended instantly what the situation was, and knew the necessity for silence. Already Dick's hands were seeking for the deerskin thongs that bound the wrists of his comrade to the tree. As soon as he had made certain, the pressure of the sharp blade instantly severed the restraining cords and set Roger's hands free. All that remained now was to do the same service with regard to the hide rope that went around Roger's waist, and then around his ankles further down. After that they could listen for a minute, to make sure they had not been heard, and then depart from the hostile camp on hands and knees, creeping stealthily along like a couple of snakes. So far Dick's cleverly arranged plan had worked admirably. If the rest proved to be as easy of accomplishment they could congratulate themselves on having done a big thing, with credit to their education in the line of border cunning. Dick had just finished severing the last of the bonds, and Roger was in the act of stepping forward, when something suddenly occurred that thrilled both boys to the heart, as well as put a different aspect on their method of hasty departure. From some place back in the woods a little way a loud and singular whoop rang forth. Dick believed that it must be intended as a signal announcing an attack; for, hardly had it ceased to ring through the aisles of the forest, than a deafening chorus of wild yells rang forth, together with the rush of many bodies crashing through the underwood and advancing from every direction toward the camp of the Dacotahs. CHAPTER XVII SHELTER IN A HOLLOW TREE "IT is the Shoshone war-cry!" exclaimed Roger, instinctively, as he heard the piercing, bubbling sound that must have been uttered with a hand to the mouth.