"Purdy!" he whispered incisively; "somethin's rotten! One cayuse; two men. Wait a minute!" and he sent his thoughts racing over every possibility. "They can be strangers that blundered through here; or friends of Nelson's. If they was strangers, an' passed th' Buttes, as that back trail indicates, they wouldn't try to keep hidden, an' either Art or Frank would 'a' seen them, an' follered them. If they was friends of his--d--n it! Wish I had taken th' trouble to hunt up th' tracks of that black cayuse some place where they showed up plain an' deep!" Purdy thoughtfully rubbed his head. "Mebby that cayuse wandered down, an' th' boys led it off to hide it." "_Both_ of 'em?" snapped Quigley. "One had to stay on guard. An' they can't turn boots into moccasins. Cuss it! Why would innercent strangers wear moccasins in this kind of country? They wouldn't, unless they was up to some deviltry. Purdy, we got a job on our hands. First, we'll see Art an' Frank--no _we_ won't: _I_ will. You foller these tracks an' find out what you can. Don't foller 'em longer than an hour. We'll meet right here. If you hear three shots so close together that they sound like a ripple, you cut h--l-bent for th' ranch, by a roundabout way," and he was gone before Purdy could answer him. Purdy ran forward, his gaze on the ground, and every time the trail became lost on clean, hard rock, he swore impatiently and ran in ever-widening circles until he found it again. Suddenly he crouched low and froze in his tracks. In an opening at the bottom of a deep, heavily wooded draw lying just ahead of him he caught sight of a black horse, saddled, cropping grass. The animal threw up its head, looked at him, flattened its ears and backed away, ready to bolt. And under his eyes lay four pairs of moccasin prints, two of them pointing back toward the Buttes. "It's _his_ bronc!" growled Purdy under his breath. "How th' devil--!" Wild conjectures filed into his mind in swift confusion, and, wrestling with them, he wheeled sharply and dashed back the way he had come, his Colt ready for action. Quigley, calling into play every trick of woodcraft that he knew, kept on toward the Twin Buttes canyon, silent, alert, never once leaving cover. The smoke of the fire up on the butte was barely discernible now and the smoke from the rustlers' fire at the foot of the trail could not be seen at all. Eagerly he scrutinized the tops of the two buttes, but in vain.