Nominally, a fictional story of the disputes between a railroad and ranchers in California, it was actually a stern critique of the Central Pacific Railroad based on the famous "Mussel Slough Tragedy" where a shootout occurred between railroad men and citizens of a small California town. The Octopus was originally planned to be part one of a three part trilogy, The Epic of the Wheat. Part two, The Pit, was published later but Norris died before completing the third novel.