"Sand's too hot fo' yore pads, dawg," said Sandy, "Raise the mischief with that tape. Shack erlong, Pronto. Give you a slice of Pedro's dried-apple pie when we git back, to make up for workin' you Sunday." The pinto tossed a pink muzzle and his master reached to pat the dusty, sweat-streaked neck. Alkali rose about them in clouds. Grit's trail, though blurred in the soft soil, was plain enough. The two riders went silently on at a steady walking gait. Talk in the saddle with men who make range-riding a business comes only in spurts. "Never see a prospector with a dawg afore," said Sam at last. "An' that a sheep dawg." "Dawg 'ud be apt to tucker out in desert travel," agreed Sandy. "Mean one more mouth fo' water." He, like Sam, speculated on the kind of man P. Casey--if it was Casey they were after--might be. If not a sheepman or a prospector, a third probability made him an outlaw, a man with a price on his head, hiding in the wilds from punishment. It sufficed to them that he was a man whom a dog loved enough to bear a call to help his master. Slowly, the mesa ahead took on more definite shape. The shadows resolved themselves into ravines and canyons. They entered a gorge filled with boulders and rounded rocks, over which the sure-footed ponies made clattering, slippery progress. Here and there the gaunt skeleton of a tree, white as if lime-washed, showed that once cottonwoods had flourished before the devouring desert had claimed the territory. The cactus was all prickly pear, the gray-green flesh of the flat leaves starred with brilliant blossom. Along one side of the canyon, mounting zigzag, showed the remains of a road, broken down by landslip and the furious rush of cloud-burst waters. Making this, finding it free of wagon sign or horse tracks, Sandy picked up Grit's trail once again. The collie wriggled, shot up its muzzle, whined, licked Sandy's face. "Nigh there," suggested Sam. Sandy nodded and let the dog get down. Grit raced off, nose high, streaking around a curve. When they reached it he was out of sight. The road had been built up in places on the outer edge with stones, dry-piled. They had fallen away, the grade following, so that sometimes all that was left for passage was a ledge along which the horses sidled carefully in single file, stirrups brushing the inside bank. The zigzags ended, the canyon narrowed, deepened. Sandy looked down to the dry bed of it four hundred feet below. The road rose at a steep pitch, cliff to the right, precipice to the left, stretching on and up to the summit of the pass.