In 1888, cowboy Steve Landry, who is actually The Durango Kid, masked champion of law and order, rides his horse along the western trail drives, where bands of renegade cowboys have been terrorizing cattle herders. En route to the town of Split Rock, where he is to become the new sheriff, Steve chases away a gang of outlaws who have shot an old man named Jenkins. He then escorts the injured man and his fifteen-year-old daughter Elaine to Split Rock. While Jenkins recuperates, Steve takes Elaine to meet his friend Smiley Burnette, a blacksmith. After deputizing Smiley, Steve recognizes the pinto hitched in front of Belle Madden's Crystal Palace saloon as the one belonging to the man who shot Jenkins. When Steve enters the saloon and tries to arrest Curley, the owner of the pinto, a fistfight between the two men ensues. Curley escapes through the rear door of the saloon, and Steve and Smiley round up a posse to chase after him. Steve eventually catches up with Curley, but because the outlaw has crossed the state line, Steve is prevented from making a legal arrest. Undaunted, Steve leaves the outlaws momentarily to change into his Durango Kid disguise, and returns to capture Curley. After delivering Curley to the town jail, Steve changes back into his cowboy clothes and watches Smiley demonstrate his new automatic jail cell lock. That night, Steve discovers that Jim Clayburn, the president of the Tavern Keepers' Association, is the leader of the outlaws, and that Belle is also in league with them. The following day, Clayburn instigates a riot to divert attention away from the jail house, and then attempts to free Curley. The jailbreak fails, however, when Clayburn is unable to break the automatic lock. Clayburn later gets an idea to kidnap Elaine to force Steve to come to his hideout, but Belle, who has grown fond of Elaine, persuades the outlaw to fake the girl's kidnapping while the girl is in her care. While Steve, dressed in his Durango Kid disguise, sets out in pursuit of the kidnappers, Smiley learns that Elaine is in Belle's back room. Smiley races after Steve, alerts him to Clayburn's trap, and then helps his pal fight off the outlaws in a gun battle. Clayburn and his cohorts hurry back to town, where they attempt to capture Elaine and use her as a hostage. Their attempt fails when Elaine escapes, and Belle is shot trying to protect her. When Elaine warns Steve that Clayburn is planning an ambush, Smiley and Steve, as The Durango Kid, outwit the outlaws and prove victorious in a gun battle. With peace finally restored to Split Rock, Steve bids farewell to his pals and leaves town.