After the Harvey Dawson gang robs a Union Pacific train of fifty thousand dollars in gold bullion, railroad detective Sunset Carson goes undercover to infiltrate the gang. To help establish Sunset's cover as the outlaw Jim Parker, the Union Pacific's chief detective chases him off a train and through the streets of a small western town. Sunset's escape is abetted by the lovely Jill Layton (Peggy Stewart), who was amused by Sunset during the train ride.