The film portrays two conflicts that take place around Flagstone, a fictional town in the American Old West - a land battle related to the construction of a railroad, and a mission of vengeance against a cold-blooded killer. A struggle exists for Sweetwater, a piece of land in the desert outside Flagstone that contains the region's only other water source. The land was bought by Brett McBain, who foresaw that the railroad would have to pass through that area, to provide water for the steam locomotives. When crippled railroad tycoon Morton learns of this, he sends his hired gun Frank to intimidate McBain to move off the land, but Frank instead kills McBain and his three children, planting evidence to frame the bandit Cheyenne (Robards). Meanwhile, former prostitute Jill arrives at Flagstone from New Orleans, revealing that she was McBain's new wife, and therefore the new owner of the land.