There was cover everywhere. Kirby's first move after pulling both himself and the horse away from the spring, was to glance up the long, deeply shaded canyon which he had entered--a gash hacked into the breast of the steep mountain as by a titanic ax. Then, reassured as to the possibilities for a defensive retreat, he glanced back toward the dazzling, bare plateau. * * * * * It was what he saw taking place amongst the sombreroed bandits out there which made the grin of satisfaction fade from his broad mouth. His last glance backward, before bolting into the canyon mouth, had showed him a ragged squadron of men left far behind, yet galloping after him still. But now-- Presently a puzzled frown made wrinkles in Freddie Kirby's wide sunburned forehead. He relaxed his grip upon the heavy Luger, which, in his big hands, looked like a cap pistol, and rubbed his eyes. But he was not mistaken. The horsemen had halted! Out there on the glaring, alkali-arid plateau, they were standing as still as so many statues. Looking toward the canyon mouth which had swallowed their quarry, they certainly were, but they were halted as completely as men struck dead. "Huh," Kirby grunted, and scratched behind his ear. The next second he swung around to look at his horse, uncertain what he was going to do next, but aware of the fact that right now, with a lot of unknown country between himself and Castanar's sunlit patio, the stallion was going to be a friend in need. As he turned, however, prepared to take up the loose reins, something else happened. The stallion let out a neigh as shrill as a trumpet blast. As Kirby jumped, grabbed for the bridle, his fingers found empty air. Like a crazy animal the stallion leaped past him, barely missing him. Out toward the plain the horse jumped, out and away from the shaded canyon mouth, out toward the spot where other horses waited. And despite the animal's blown condition, the speed he put into his retreat left Kirby dazed. * * * * * After a helpless, profanity-filled second, Kirby scratched behind his ear again. As certain as the fact that almost his sole hope of getting back to civilization depended upon the stallion, was the fact that the brute did not intend to stop running until he dropped. "Now what in the hell ever got into his crazy head?" Kirby muttered grimly. Then he turned around to glance up the shadow-filled slash of a canyon, and sniffed. "Huh!" Faintly in the air had risen an odor the like of which he had never encountered in his life. A combination, it was, of the unforgetable stench which hangs over a battlefield when the dead are long unburied, and of a fragrance more rare, more heady, more poignantly sweet than any essence ever concocted by Parisian perfumer. With the drifting scent came a sound. Faint, carrying from a distance, the rumble which Kirby heard was almost certainly that of a geyser.