the vast space beyond the
arroyo edge. Sanderson saw the outlines of animal and rider as they
appeared for an instant, partly screened from him by the trees and
undergrowth on the arroyo edge. Then horse and rider vanished, going
northward, away from the arroyo, silently, swiftly.

Schooled to caution by his long experience in a section of country where
violence and sudden death were not even noteworthy incidents of life, and
where a man's safety depended entirely upon his own vigilance and wisdom,
Sanderson got up carefully, making no noise, slipped around the thicket
of alder, crouched behind a convenient rock, huge and jagged, and waited.

Perhaps the incident was closed. The rider might be innocent of any evil
intentions; he might by this time be riding straight away from the
arroyo. That was for Sanderson to determine.

The rider of the horse--a black one--had seemed to be riding stealthily,
leaning forward over the black horse's mane as though desirous of
concealing his movements as much as possible. From whom?

It had seemed that he feared Sanderson would see him; that he had
misjudged his distance from the gully--thinking he was far enough away to
escape observation, and yet not quite certain, crouching in the saddle to
be on the safe side in case he was nearer than he had thought.

Sanderson waited--for only a few minutes actually, but the time seemed
longer. Then, just when he was mentally debating an impulse to climb to
the top of the gully, to see if the rider was in sight, he heard a sound
as of a heavy body crashing through some underbrush, and saw two riders
skirting the edge of the arroyo near him.

They halted their horses back of the spruce trees near the arroyo edge.
The rank undergrowth in the timber prevented them seeing Sanderson's
horse--which was further concealed by the thicket of alder. The men,
however, did not look into the arroyo. Their attention and interest
appeared to be centered upon the actions of the first horseman. Sitting
erect in their saddles, they shaded their eyes with their hands and gazed
northward.

After a short look, one of the men laughed, unpleasantly.

"Sneakin'--he is," said the one who laughed. "Knows we're campin' on his
trail, an' reckons on givin' us the slip. I never thought Bill would go
back on his friends thataway. We'll make him sweat, damn him!"

The other cursed, also. "Hoggin' it, he is," he said. "I ain't never
trusted him. He won't