It was clear that all were concerned in a personal quarrel which was no concern of Sanderson's.

It was also apparent to Sanderson that the two men who had halted at the edge of the arroyo were not of the type that contributed to the peace and order of the country.
Plainly, they were of the lower strata of riffraff which had drifted into the West to exact its toll from a people who could not claim the protection of a law that was remote and impotent.
Sanderson suspected that the first rider had been concerned in some lawless transaction with the other two, and that the first rider had decamped with the entire spoils.

That much was indicated by the words of the two.

Dire punishment for the first man was imminent.
Sanderson had no sympathy for the first rider.

He felt, though, a slight curiosity over the probable outcome of the affair, and so, working rapidly, he broke camp, threw saddle and bridle on the white horse, strapped his slicker to the cantle of the saddle, and rode the brown horse up the slope of the arroyo, taking the direction in which the three men had disappeared..