It was these questions which caused the youth to suspect that the fire might have been started by his father. True, he had expressed a disbelief in this view when given by Tim, but that was before the later phase had dawned upon him. It looked like a rash act on the part of the rancher, if he had performed it, but there might be excuse for his appealing to the signal that he had employed in a former instance to apprise his son of his location. Speculation and guessing, however, could go on forever without result. There was but one way of learning the truth, and that was to investigate for himself. Prudence demanded that the Sioux at the base of the ridge should be given no inkling of his intention; and, in order to prevent it, a long detour was necessary to take him out of their field of vision. Accordingly he turned so as to follow a course parallel to the ridge, and breaking into a swift canter kept it up until, when he turned in the saddle and looked back, not the first sign of the hostiles was visible. He was now miles distant, too far to return on foot, even had he felt inclined to abandon Jack and try it alone. He rode close to the base of the ridge, whose curving course was favorable, and facing about started back toward the point he had left after his survey of the party that held Tim Brophy a prisoner. He did not believe there was any special danger in this, for he had only to maintain a sharp lookout to detect the Sioux, if they happened to be journeying in that direction. The broad stretch of open plain gave him every chance he could ask to turn the fleetness of Jack to the best account: and he feared no pursuit that could be made, where he was granted anything like a chance. His purpose was to approach as near the spot as was prudent, provided they remained where he last saw them, and then, dismounting, penetrate nigh enough to learn the meaning of the smoke which was such an interesting fact to him. The task was a difficult one, for it was more than probable that by the time he reached the neighborhood of the signal fire it would be extinguished; for certainly his father would not continue the display after it had failed in its purpose, and the appearance of the hostiles showed him that it was liable to do more harm than good. CHAPTER XXIX. A BREAK FOR FREEDOM. Accustomed as are the Sioux to scenes of violence, it is not probable that any members of the party to whom we have been referring ever looked upon a sight so remarkable as the prairie duel between Starcus and the young rancher. This Indian, who had come among his native people in the hope of staying the tide of frenzy sweeping through the tribe, was himself carried away by the craze, and from a peaceable, well-educated youth became among the most violent of those that arrayed themselves against the white man.