But suddenly Wildfire broke that silence with a whistle which to Slone's overstrained faculties seemed a blast as piercing as the splitting sound of lightning. And with the whistle Wildfire plunged up toward the pass. Slone yelled at the top of his lungs and fired his gun before he could terrorize the stallion and drive him back down the slope. Soon Wildfire became again a running black object, and then he disappeared. The great line of fire had gotten beyond the monuments and now stretched unbroken across the valley from wall to slope. Wildfire could never pierce that line of flames. And now Slone saw, in the paling sky to the east, that dawn was at hand. CHAPTER VII Slone looked grimly glad when simultaneously with the first red flash of sunrise a breeze fanned his cheek. All that was needed now was a west wind. And here came the assurance of it. The valley appeared hazy and smoky, with slow, rolling clouds low down where the line of fire moved. The coming of daylight paled the blaze of the grass, though here and there Slone caught flickering glimpses of dull red flame. The wild stallion kept to the center of the valley, restlessly facing this way and that, but never toward the smoke. Slone made sure that Wildfire gradually gave ground as the line of smoke slowly worked toward him. Every moment the breeze freshened, grew steadier and stronger, until Slone saw that it began to clear the valley of the low-hanging smoke. There came a time when once more the blazing line extended across from slope to slope. Wildfire was cornered, trapped. Many times Slone nervously uncoiled and recoiled his lasso. Presently the great chance of his life would come--the hardest and most important throw he would ever have with a rope. He did not miss often, but then he missed sometimes, and here he must be swift and sure. It annoyed him that his hands perspired and trembled and that something weighty seemed to obstruct his breathing. He muttered that he was pretty much worn out, not in the best of condition for a hard fight with a wild horse. Still he would capture Wildfire; his mind was unalterably set there. He anticipated that the stallion would make a final and desperate rush past him; and he had his plan of action all outlined. What worried him was the possibility of Wildfire doing some unforeseen feat at the very last. Slone was prepared for hours of strained watching, and then a desperate effort, and then a shock that might kill Wildfire and cripple Nagger, or a long race and fight.