Trampas is sent by stagecoach on a cattle buying trip. At a way station two soldiers and a payroll join the stage and they are told there may be Indian trouble ahead. When the coach stops for rest and water, Trampas finds Jason Adams standing in the river over the dead body of the ferry man from Diablo Crossing where the stage is headed. At Diablo Crossing they find the ferry destroyed and Bud McLister and Marcy McLister who are brother and sister. While repairing the ferry, Trooper Rankin takes a shine to Marcy, they are shot at, and the horses disappear followed by the payroll.
