He had planned to intercept the men where the trail crossed this arroyo, or, should the trail show pony tracks, to follow them into the desert beyond, where, sooner or later, he would overtake them. They had a start of twelve hours, but Waring reasoned that they would not do much riding in daylight. The trail at the northern end of the cañon had shown no fresh tracks that morning. His problem was simple. The answer would be definite. He returned to the shelter of the brush, dropped the glasses into a saddle-pocket, and stretched himself wearily. A few yards below him, on a brush-dotted level, his horse, Dexter, slowly circled his picket and nibbled at the scant bunch-grass. The western sun trailed long shadows across the cañon; shadows that drifted imperceptibly farther and farther, spreading, commingling, softening the broken outlines of ledge and brush until the walled solitude was brimmed with dusk, save where a red shaft cleft the fast-fading twilight, burning like a great spotlight on a picketed horse and a man asleep, his head pillowed on a saddle. As the dusk drew down, the horse ceased grazing, sniffed the coming night, and nickered softly. Waring rose and led the horse to water, and, returning, emptied half the grain in the morral on a blanket. Dex munched contentedly. When the horse had finished eating the grain, Waring picketed him in a fresh spot and climbed back to the ledge, where he sat watching the western wall of the cañon, occasionally glancing up as some dim star burned through the deepening dusk and bloomed to a silvery maturity. Presently a faint pallor overspread the cañon till it lay like a ghostly sea dotted with strange islands of brush and rock; islands that seemed to waver and shift in a sort of vague restlessness, as though trying to evade the ever-brightening tide of moonlight that burned away their shrouds of dusk and fixed them in still, tangible shapes upon the cañon floor. Across the cañon the farther trail ran past a broad, blank wall of rock. No horseman could cross that open space unseen. Waring, seated upon the ledge, leaned back against the wall, watching the angling shadows shorten as the moon drew overhead. Toward morning he became drowsy. As the white radiance paled to gray, he rose and paced back and forth upon the narrow ledge to keep himself awake. In a few minutes the moon would disappear behind the farther rim of the world; the cañon would sink back into its own night, all its moonlit imageries melting, vanishing. In the hour before dawn Waring would be unable to see anything of the farther wall save a wavering blur.