Golden Lightning by Max Brand

Menneval, the most feared killer in Alaska, had sent Lefty Bill Ranger all the way to California looking for two men. Their names were Peter and Oliver Crosson, father and son. Menneval just wanted information—he said. But when Lefty got to where the Crossons were supposed to be, nobody could tell him anything about them. Then he stumbled upon them himself and became involved in a fantastic adventure. There was death in the air and blood on the wind, and at the last moment—there was Menneval, in person, come to seal his bargain.