In California, the Southern Pacific Railway is prying the West wide open, and the land is worth its weight in gold. While some men get in on the action, and some get out of the way, one group of settlers is making a stand--and holding up the railway. Turning to Alan Pinkerton's Chicago detective agency, the railroad robber barons hire the perfect agent to penetrate the settler's organization, a man who learned a spy's trade in the Civil War.