In late 1890s Wyoming, Butch Cassidy is the affable, clever, talkative leader of the outlaw Hole in the Wall Gang. His closest companion is the laconic dead-shot "Sundance Kid". As the west rapidly becomes civilized, the law finally catches up to Butch, Sundance and their gang. Chased doggedly by a special posse, the two decide to make their way to South America in hopes of evading their pursuers once and for all.
Aging outlaw Pike Bishop (William Holden) prepares to retire after one final robbery. Joined by his gang, which includes Dutch Engstrom (Ernest Borgnine) and brothers Lyle (Warren Oates) and Tector Gorch (Ben Johnson), Bishop discovers the heist is a setup orchestrated in part by his old partner, Deke Thornton (Robert Ryan). As the remaining gang takes refuge in Mexican territory, Thornton trails them, resulting in fierce gunfights with plenty of casualties
The murder of her father sends a teenage tomboy, Mattie Ross (Kim Darby), on a mission of "justice", which involves avenging her father's death. She recruits a tough old marshal, "Rooster" Cogburn (John Wayne), because he has "grit", and a reputation of getting the job done. The two are joined by a Texas Ranger, La Boeuf (Glen Campbell), who is looking for the same man (Jeff Corey) for a separate murder in Texas. Their odyssey takes them from Fort Smith, Arkansas, deep into the Indian Territory (present day Oklahoma) to find their man.