The Dakota Kid.

Dakota Kid is a young outlaw who joins a gang headed by Ace Crandall. Crandall's aim is to unseat Sheriff Tom White and then use his power to enrich himself at the community's expense. Dakota impersonates a long-lost nephew of the sheriff, and is made a marshal. Through his association with the sheriff's grandson, Red White and his friend Judy, plus falling in love with Mary Lewis, the Kid gradually reforms.