Would it be that they held a secret there they did not wish known, and so would resist the intrusion of others? It might be, and that a death-struggle would follow the discovery of their retreat. Still, Buffalo Bill was not one to dread whatever might turn up, and he had seen Doctor Dick tried and proven true as steel and brave as a lion. And so the search continued, the scout unerringly clinging to the trail until, just as the two felt that the retreat of those mysterious dwellers in the Grand Canyon was almost before them, they came upon a sight that caused them to draw rein and sit upon their horses appalled at the scene presented to their view. What they saw was the fallen cliff, and there, just peering out from among the piles of rocks, was the shattered end of a stout cabin. They had found the secret retreat, but they stood there feeling that those who had dwelt in that ruined cabin were beyond all human eye, buried beneath a monument of rocks an army could not remove in weeks. "And this is the end?" said Buffalo Bill, the first to speak, breaking a silence that was appalling. "Yes, his end, for he undoubtedly lies buried there beneath that mass of rocks. If it is my foe, Wallace Weston, who has met such a fate, so let it be." The two did not tarry long in the canyon, for a dread of the weird spot seemed to have come over them both. Doctor Dick roamed about, picking up bits of rock and examining it closely, while he muttered: "It was a gold-mine that held them here, but that falling cliff has hidden the secret forever." And Buffalo Bill went about searching for trails, yet made no comment, whether he found any or not, to indicate that the lone dwellers in the canyon had not both perished in their cabin, and lay buried beneath the hills of rock that had fallen from the heights above the valley. But, as the two men rode away up the dangerous mountain-trail, there were eyes peering upon them they little dreamed of, and Wallace Weston muttered: "They believe me dead now: so let it be." CHAPTER IV. A VOW OF VENGEANCE. The night after leaving the Grand Canyon, Buffalo Bill and Doctor Dick camped again at the rendezvous of the deserted camp, which was marked by the grave of Black-heart Bill. The two friends talked until a late hour into the night, though they intended making an early start in the morning for their respective homes, the scout going to the fort, the doctor to Last Chance. "Well, Cody, you were satisfied before that Sergeant Wallace Weston was dead, that he died in the desert, but you yielded to my belief that he lived and was none other than the Hermit of the Grand Canyon who came to your rescue some time ago; but now you are assured that, the hermit-miner being buried beneath the walls of his cabin, there is no doubt left that, if he really was Wallace Weston, he is surely not among the living?"