When Johnny Nelson reached the twin boulders marking the beginning of the sloping run where the trail pitched down, he grinned happily at sight of the moon rising over the low hills and then grabbed at his holster, while every hair in his head stood up curiously.  A wild, haunting, feminine scream arose to a quavering soprano and sobbed away into silence.  No words can adequately describe the unearthly wail in that cry and it took a full half-minute for Johnny to become himself again and to understand what it was.  Once more it arose, nearer, and Johnny peered into the shadows along a rough backbone of rock, his Colt balanced in his half-raised hand.

“You come ‘round me an’ you’ll get hurt,” he muttered, straining his eyes to peer into the blackness of the shadows.  “Come on out, Soft-foot; the moon’s yore finish.  You an’ me will have it out right here an’ now—­I don’t want no cougar trailing me through that ink-black canyon on a two-foot ledge—­” he thought he saw a shadow glide across a dim patch of moonlight, but when his smoke rifted he knew he had missed.  “Damn it!  You’ve got a mate ’round here somewhere,” he complained.  “Well, I’ll have to chance it, anyhow.  Come on, bronc!  Yo’re shaking like a leaf—­get out of this!”

When he began to descend into the canyon he allowed his horse to pick its own way without any guidance from him, and gave all of his attention to the trail behind him.  The horse could get along better by itself in the dark, and it was more than possible that one or two lithe cougars might be slinking behind him on velvet paws.  The horse scraped along gingerly, feeling its way step by step, and sending stones rattling and clattering down the precipice at his left to tinkle into the stream at the bottom.

“Gee, but I wish I’d not wasted so much time,” muttered the rider uneasily.  “This here canyon-cougar combination is the worst I ever butted up against.  I’ll never be late again, not never; not for all the girls in the world.  Easy, bronc,” he cautioned, as he felt the animal slip and quiver.  “Won’t this trail ever start going up again?” he growled petulantly, taking his eyes off the black back trail, where no amount of scrutiny showed him anything, and turned in the saddle to peer ahead—­and a yell of surprise and fear burst from him, while chills ran up and down his spine.  An unearthly, piercing shriek suddenly rang out and filled the canyon with ear-splitting uproar and a glowing, sheeted half-figure of a man floated and danced twenty feet from him and over the chasm.  He jerked his gun and fired, but only once, for his mount had its own ideas about some things and this particular one easily headed the list.  The startled rider grabbed reins and pommel, his blood congealed with fear of the precipice less than a foot from his side, and he gave all his attention to the horse.  But scared as he was he heard, or thought that he heard, a peculiar sound when he fired, and he would have sworn that he hit