An injured railroad baron, Morton (Gabriele Ferzetti) wants to get his hands on prominent land currently occupied by Brett McBain (Frank Wolff). To get Brett out of the picture permanently, Morton hires a killer by the name of Frank (Henry Fonda) to carry out the deed. Morton's plans are soon foiled when he learns of Brett's new bride Jill, who has inherited everything, including the land.
Outlaws Cheyenne (Jason Robards) and Harmonica (Charles Bronson) take it upon themselves to protect Jill from Morton, each for their own ulterior motives.