While holding up the small Western town of Powder River, Tommy Ryland disobeys orders given by his outlaw stepfather, Pop Ryland, and later threatens to quit crime altogether. Pop, whose next big scheme is to counterfeit territorial bonds, angrily prohibits Tommy from quitting and throws a punch at him. Pop's sons, Dave and Clint, then persuade their father to hire McCall, a professional gunman, to kill Tommy. At Ben Trask's saloon, cowboy Steve Lacey decides to investigate McCall and the Rylands when he overhears McCall discussing a letter he received from Pop. Unknown to anyone in the town, Steve is the famous Durango Kid, the masked enemy of all outlaws. After putting on his Durango Kid disguise, Steve pursues McCall, engages him in a fistfight and steals the letter he received from the Rylands. Dressed in his regular clothes, Steve then goes to the Rylands and presents himself as the killer-for-hire sent by Trask. Steve soon wins Pop's trust, and after Pop gives him information about the next stagecoach holdup, Steve puts on his Durango Kid disguise and foils their plan. Realizing that the Rylands have begun to suspect him, Steve promises Pop that he will kill Tommy right away. Instead of murdering Tommy, though, Steve stages a fake killing and takes Tommy to a hiding place, where his girl friend, Mollie Parnell, awaits him. Though Pop falls for Steve's trick, Clint continues to suspect him. The Rylands later capture Steve's barber pal, Smiley Burnette, and accuse him of tipping off The Durango Kid, but just as they are about to force a confession from him, Steve, dressed as The Durango Kid, rides up and frees him. Noticing the printer's ink stain on Smiley's clothes, Steve concludes that the Rylands are involved in a counterfeiting scheme, and goes to their house to investigate. Steve and Tommy search the house for clues, and soon find the printing presses used to counterfeit the territorial bonds. While Tommy chases Pop and Dave, Clint discovers Steve in the house and accuses him of being The Durango Kid. Clint then reaches for his gun, but Steve beats him to the draw and kills him. After Steve shoots Dave, Pop offers to surrender. Once outside the house, though, Pop reaches for his gun and prepares to shoot Steve, but he is shot before he is able to take aim. With the outlaws killed, Steve resumes his life as a cowboy, and Tommy and Mollie resume their romance.