Gunfighter Cole Thornton rides into the frontier town of El Dorado and is reunited with J. P. Harrah, an old friend who is now the local sheriff. Thornton has been sent for by cattle baron Bart Jason, but he refuses to work for the man when J. P. informs him that his job will be to drive the MacDonald family off their land, which Jason needs for water. When Cole is ambushed while riding back from the Jason ranch, he wounds one of Kevin MacDonald's four sons, who shoots himself to escape the pain. Before Cole can explain the incident to MacDonald's hoydenish daughter, Joey, the young woman shoots him. The bullet lodges itself close to Cole's spine, and old "Doc" Miller feels unqualified to remove it and suggests he see a more equipped surgeon. Sometime later, at a cantina near the Mexican border, Cole strikes up a friendship with a young drifter named Mississippi. He also meets Jason's new hired gunman, Nelse McLeod, and learns that J. P. has been drunk ever since being jilted by a dancehall girl. Accompanied by Mississippi, Cole rides back to El Dorado and attempts to sober up J. P. with a liquid concoction laced with gunpowder. An effort to restore peace by jailing Jason and driving McLeod out of town is temporarily successful, but they return, capture Cole, and then trade him for Jason. As the inevitable showdown nears, Cole's right hand becomes partially paralyzed because of the bullet near his spine; and J. P. is forced to hobble around on crutches because of a leg wound. Aided by J. P.'s wizened arrow-shooting deputy, Bull Harris, and the fiery Joey, they manage to kill Jason, McLeod, and the entire gang. With peace restored, Mississippi decides to settle down with Joey; Cole resumes his longtime courtship of Maudie, El Dorado's saloon proprietress; and the now-sober J. P. basks in his renewed self respect.