stretch of desert.

Sanderson started to get to his feet. Then he sat down again, stiffening
slowly, his right hand slipping quickly to the butt of the pistol at his
right hip. His chin went forward, his lips straightened, and his eyes
gleamed with cold alertness.

A horseman had appeared from somewhere in 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