Ramon turned and put his horse up the slope, Dex following. Waring curled behind a rock and swept the valley with his glass. The heads of several rurales were visible in the brush. They had halted and were looking for tracks. Finally one of them raised his arm and pointed toward the hill. They had caught sight of Ramon on the slope above. Presently three riders appeared at the foot of the grade. It was a long shot from where Waring lay. He centered on the leading rural, allowed for a chance of overshooting, and pressed the trigger. The carbine snarled. An echo ripped the shimmering heat. A horse reared and plunged up the valley, the saddle empty. Waring rose, and plodded up the slope. "Three would have trailed us. Two will ride back to the railroad and report. I wonder how many of them are bushed along the trail between here and Nogales?" In the American custom-house at Nogales sat a lean, lank man gazing out of a window facing the south. His chair was tilted back, and his large feet were crossed on the desk in front of him. He was in his shirt-sleeves, and he puffed indolently at a cigar and blew smoke-rings toward the ceiling. Incidentally his name was known throughout the country and beyond its southern borders. But if this distinction affected him in any way it was not evident. He seemed submerged in a lassitude which he neither invited nor struggled against. A group of riders appeared down the road. The lean man brushed a cloud of smoke away and gazed at them with indifference. They drew nearer. He saw that they were Mexicans--rurales. Without turning his head, he called to an invisible somebody in the next room. "Jack, drift over to the cantina and get a drink." A chair clumped to the floor, and a stocky, dark-faced man appeared, rubbing his eyes. "On who?" he queried, grinning. "On old man Diaz," replied the lean man. "All right, Pat. But mebby his credit ain't good on our side of the line." The lean man said nothing. He continued to gaze out of the window. The white road ran south and south into the very haze of the beyond. His assistant picked up a hat and strolled out. A few doors down the street stood several excellent saddle animals tied to the hitching-rail in front of the cantina. He didn't need to be told that they were the picked horses of the rurales, and that for some strange reason his superior had sent him to find out just why these same rurales were in town.