Leaving this concealment after dark, he rode straight for the hills. He did not need to look for the outlaw trail; for, with his field glass, just before sunset, he had discovered the gap where it entered the rougher country. He expected to find a sentinel posted in the pass. So, when, after muffling the hoofs of Midnight, he had advanced as near as he deemed prudent, he left the horse and crept forward on foot. “Ah,” he said, as, after stealing forward some distance, he lay in the shadow of a rock, listening and watching, “the sentinel is there, just as I expected! That shows another thing, too: the lair of these prairie wolves isn’t so very far from here.” The sentinel seemed but a shadow himself, as he stood in that shadow. Only a trained eye could have detected his presence, or would have thought him other than a part of the rocky wall against which he stood. But to the keen vision of the scout he was as distinct as the great rock itself. For a full minute after locating the man Buffalo Bill lay still, thinking how best to approach or circumvent him. Then, with knife in his teeth, and the lariat, which he had taken from the saddle, in his hands, and held ready for use, he slipped on, silent as a weasel stealing on its prey. It was necessary to silence that sentinel. Otherwise an alarm would be given, which would arouse the outlaws and keep Buffalo Bill from carrying out the plans that he had half formed. The unsuspecting sentinel seemed to be looking straight at the scout; but his attitude of careless ease and security showed that he did not dream that a foe was within miles of him. In truth, so perilous was the task of approaching the outlaw stronghold that even Ricardo himself did not believe any pursuit would be made. He would have laughed at the thought of one man making that pursuit, as Buffalo Bill had done. Besides, Ricardo had been at some pains to hide his trail on the prairie, and was sure that it could not be picked up easily. The posting of the sentinel was, therefore, but a matter of camp routine. So slowly that he seemed scarcely to move, and so quietly that he made no more noise than the falling of a leaf, the scout drew inch by inch nearer to the man he had marked for his prey. And the sentinel, wrapped in a sense of security, thought danger so far away and his position such a sinecure that he began to roll a cigarette. Buffalo Bill was but fifteen feet away when the sentinel struck a match. In doing this, the sentinel turned to the wall behind him, and, as he puffed at the cigarette, he held one hand up to keep the match from being blown out. At that moment Buffalo Bill rose silently to his feet. The lariat was given one quick swing, and the noose shot for the stooped head of the sentinel. The match went out, as if it had been struck from his hand, as the noose fell over his head and was pulled tight by a quick jerk.