In "The Valley of Thunder," range men have been bursting into Dunningan, Wyoming, scattering pedestrians, spoiling for trouble even when they have not been drinking and more when they have. Marshal Hugh Mitchell's job is to put an end to this chaos. The problem is not simply the rowdy range men, but also the owners of the ranches. They are not about to have their power questioned or challenged by law enforcement and are unwilling to have any restraint whatsoever imposed on their men by anyone.