western distance,
when Purgatory whinnied lowly.

Flashing around in the saddle, the rider again faced the rock. And he saw
movement there now. The distance was great, but the clarity of the
atmosphere brought a moving object distinctly into his vision. The object
was a man, and, like a huge fly, he was crawling rapidly up the sloping
side of the rock, toward its peak, which flattened abruptly at the
summit.

The man bore a rifle. The rider could see it dragging from the man's
hand; and in a flash the rider was out of the saddle, throwing himself
flat behind a low ridge of sand, his own rifle coming to a rest on a
small boulder as he trained its muzzle upon the man, who by this time had
reached the summit of the rocks in the distance. The rider waited,
nursing the stock of the rifle, his eyes blazing, while Purgatory,
seemingly aware of an impending tragedy, moved slowly away as though
understanding that he must not expose himself.

The rider waited, anticipating the bullet that would presently whine
toward him. And then he heard the report of the man's rifle, saw that the
smoke streak had been directed downward, as though the man on the summit
of the rock were shooting at something below him.

The rider had been pressing the trigger of his own weapon when he saw the
smoke streak. He withheld his fire when he divined that the man was not
shooting at him; and when he saw the man on the rock shoot again--downward
once more--the rider frowned with embarrassment.

"Don't even know I'm here!" he mused. "An' me gettin' ready to salivate
him!"

He got to his knees and watched, curiosity gleaming in his eyes. He saw
the man on the rock fire again--downward--and he noted a smoke spurt
answer the shot, coming upward from the base of the rock. The rider got
to his feet and peered intently at the rock. And now he saw another man
crouching near its base. This man, however, was not the one the man on
the summit of the rock was shooting at, for smoke streaks were issuing
from a weapon in that man's hand also, but they were horizontal streaks.

Therefore the rider divined that the two men must be shooting at another
who was on the far side of the rock; and he ran to Purgatory, speaking no
word until he had vaulted into the saddle. Then he spoke shortly.

"They're white men, Purgatory, an' they're havin' a private rukus, looks
like. But we're doin' some investigatin' just to see if the game's on the
level."

CHAPTER II