Jim McKinnon, a bandit known as "The Sundown Kid," is pressured by his dancer girl friend Nita to give himself up. Nita thinks that because Jim has only committed robbery and not murder, he will receive a short sentence and they can then start a new life together. Jim refuses, however, so Nita conspires with law officials to capture him at the cantina where she works. Jim kills one of the men while resisting arrest, but before the sheriff can take him away, Jim is rescued by a gang of rustlers. The rustlers tell Jim that their boss wants to see him and take him to Mark Albo, a cattle broker who secretly runs the gang. Albo explains that the new sheriff of Apache Falls, Bruce McKinnon, is too honest to let Albo's suspicious shipments of cattle go through, and therefore needs to be replaced. Albo wants Jim for the job because he bears a striking resemblance to Bruce. Jim does not explain that he is Bruce's brother but does accept Albo's proposition, because he holds a grudge against Bruce, who arrested him years earlier in an attempt to flush out the real perpetrator of a robbery. The gang captures Bruce and brings him to the hideout, where Jim changes clothes with him. Bruce is happy to see his brother, who has refused to have any contact with his family, but Jim bitterly condemns him and leaves for town. Nita, who has come to Apache Falls in search of Jim, asks deputy Jones about the Sundown Kid's whereabouts, and is thrilled to see Jim when he appears. Jim tells her that he is Bruce, however, and orders Jones to escort Nita to the stagecoach. Nita is not fooled by Jim's pretense and when she follows him to Bruce's ranch, he confesses that he is impersonating his brother. The pair reconcile, although Nita is jealous of Ruth Morton, Bruce's fiancée, to whom Jim must pay attention to keep up the act. Later that night, Ruth and Jim host a party at which she and Bruce are to announce their engagement. Nita interrupts the festivities, however, when a minister reveals that, as a surprise, Bruce had arranged to marry Ruth that night. When Nita reveals Jim's identity, Albo throws a knife at her and kills her before she can implicate him. Jim assures his mother and Ruth that Bruce will be okay then escapes before Albo's men capture him. Jim rescues Bruce from the gang's hideout and, despite his mother's pleas to stay, goes out to tackle Albo's men. Bruce rounds up a posse to help, and soon the two brothers have led their men in a successful attack against the gang. Jim is fatally wounded during the fight but as he dies, he reconciles with his brother. Soon after, Jones unwittingly arrests Bruce, and Ruth will not free him from the cell until a minister comes to marry them.