Ready to quit their life of crime, the three "most-wanted" outlaws in the West---Butch Cassidy, Sundance Kid and Bill Carver ---perform their final job by robbing and stealing a train and fleeing across the border. In a South American town they begin their life of respectability by purchasing a ranch and depositing their stolen fortune in the local bank, and throwing a big fiesta to entertain the locals, including Colonel Aguilar and his beautiful daughter Rita. During the festivities the bank is robbed by the famous outlaw El Gallo and his bandits, on information learned from informant El Rataan. Facing bankruptcy and deportation, the three outlaws stage a series of robberies made to appear as though carried out by El Gallo. Meanwhile, an American detective, Charlie Trenton, arrives and sets out with Colonel Aguilar to arrest the Americans, but they are tipped off by Rita, who has fallen in love with the Sundance Kid, and they escape. Suspecting that El Gallo is innocent of the recent robberies, Trenton persuades him to assist in capturing Cassidy, Sundance and Carver.