Dead Man's Gulch is a fast-paced western produced by Republic Pictures. After the Pony Express disbands, long-time friends Tennessee Colby (Don 'Red' Barry) and Tommy Logan (Malcolm 'Bud' McTaggart) head for Adobe Wells to make a new life. Colby becomes the Deputy Marshall and is asked to head up a congressional investigation into a series of freight-train robberies. As the investigation begins, Colby soon discovers the perpetrators of the robberies are a gang of outlaws led by Walt Bledsoe (Clancy Cooper), who has taken Tommy under his wing. Colby is torn between his friendship with Tommy and his duty to serve the law. To make matters more complicated, Colby's new girlfriend is none other than Tommy's sister, Mary Logan (Lynn Merrick). Colby initially tries to protect Tommy but all that changes when he witnesses Tommy committing cold-blooded murder. After Colby sees Tommy's true colors, not even Mary can stop him from getting his man.