He left Tank Canyon after dark, driving his pack-mules before him to detect any possible ambush; and in his nest on the front pack Good Luck stood up like a sentinel, eager to scent out the lurking foe. For the past day and night Good Luck had been uneasy, snuffing the wind and growling in his throat, but the actions of his master had been cause enough for that, for he responded to Wunpost's every mood. And Wunpost was as jumpy as a cat that has been chased by a dog, he practised for hours on the draw-and-shoot; and whenever he dismounted he dragged his rifle with him to make sure he would do it in a pinch. He was worried but not frightened and when he came free from the canyon he headed for Surveyor's Well. Someone had been there before him, perhaps even that very night, for water had been splashed about the hole; but whoever it was, was gone. Wunpost studied the unshod horse-track, then he began to cut circles in the snow-white alkali and at last he sat down to await the dawn. There was something eerie about this pursuit, if pursuit it was, for while the horse had been watered from the bucket at the well, its rider had not left a track. Not a heel-mark, not a nail-point, and the last of the water had been dropped craftily on the spot where he had mounted. That was enough--Wunpost knew he had met his match. He watered his mules again, rode west into the mesquite brush and at sun-up he was hid for the day. Where three giant mesquite trees, their tops reared high in the air and their trunks banked up with sand, sprawled together to make a natural barricade, Wunpost unpacked his mules and tied them there to browse while he climbed to the top of a mound. The desert was quite bare as far as he could see--no horseman came or went, every distant trail was empty, the way to Tank Canyon was untrod. And yet somewhere there must be a man and a horse--a very ordinary horse, such as any man might have, and a man who wiped out his tracks. Wunpost lay there a long time, sweeping the washes with his glasses, and then a shadow passed over him and was gone. He jumped and a glossy raven, his head turned to one side, gave vent to a loud, throaty _quawk_! His mate followed behind him, her wings rustling noisily, her beady eye fixed on his camp, and Wunpost looked up and cursed back at them.