The line-rider waited for no more definite warning. He waved a hand toward the rustler and shouted down the wind: "Some other day." Quickly he swung his horse to the left and vanished into an arroyo. Then, without an instant's loss of time, he put his pony swiftly up the draw toward a "rim-rock" edging a mesa. Over to the right was Box Canon, which led to the rough lands of a terrain unknown to Roberts. It was a three-to-one chance that the rustler would disappear into the canon. The young man rode fast, putting his bronco at the hills with a rush. He was in a treeless country, covered with polecat brush. Through this he plunged recklessly, taking breaks in the ground without slackening speed in the least. Near the summit of the rise Roberts swung from the saddle and ran forward through the brush, crouching as he moved. With a minimum of noise and a maximum of speed he negotiated the thick shrubbery and reached the gorge. He crept forward cautiously and looked down. Through the shin-oak which grew thick on the edge of the bluff he made out a man on horseback driving a calf. The mount was a sorrel with white stockings and a splash of white on the nose. The distance was too great for Roberts to make out the features of the rider clearly, though he could see the fellow was dark and slender. The line-rider watched him out of sight, then slithered down the face of the bluff to the sandy wash. He knelt down and studied intently the hoofprints written in the soil. They told him that the left hind hoof of the animal was broken in an odd way. Jack Roberts clambered up the steep edge of the gulch and returned to the cow-pony waiting for him with drooping hip and sleepy eyes. "Oh, you Two Bits, we'll amble along and see where our friend is headin' for." He picked a way down into the canon and followed the rustler. At the head of the gulch the man on the sorrel had turned to the left. The cowboy turned also in that direction. A sign by the side of the trail confronted him. THIS IS PETE DINSMORE'S ROAD-- TAKE ANOTHER "The plot sure thickens," grinned Jack. "Reckon I won't take Pete's advice to-day. It don't listen good." He spoke aloud, to himself or to his horse or to the empty world at large, as lonely riders often do on the plains or in the hills, but from the heavens above an answer dropped down to him in a heavy, masterful voice: "Git back along that trail _pronto_!" Roberts looked up. A flat rock topped the bluff above. From the edge of it the barrel of a rifle projected. Behind it was a face masked by a bandana handkerchief. The combination was a sinister one. If the line-rider was dismayed or even surprised, he gave no evidence of it. "Just as you say, stranger. I reckon you're callin' this dance," he admitted. "You'll be lucky if you don't die of lead-poisonin' inside o' five minutes. No funny business! Git!"