Madge Black witnesses her best friend Nan Westland, kissing her husband, successful lawyer Jeffrey Arnold Black, a successful lawyer, and orders Nan from the house. Angered by her refusal to let him explain, Jeffrey leaves his wife and son David, Jeffrey meets Nan on a westbound train. Though he does not love her he offers his protection and the next year they welcome a son, William. Nan pleads with him to divorce Madge and marry her for the sake of their son, but he will refuse. Distraught, she marries Ben Richardson, a client of Jeffrey's client, leaving their son behind. Twenty years pass with David becoming a responsible adult while half-brother William now known as “Rodeo” becomes the leader of a lawless band of robbers. Meanwhile Ben Richardson and Nan have become owners of Chanceland, a gambling-house in Colorado and it is there that things reach a climax between the near identical brothers.