Cole Thornton, played by John Wayne, is a legendary gunslinger who has arrived in the town of El Dorado to meet with his old friend, Sheriff J.P. Hara, played by Robert Mitchum. Hara informs Thornton that a wealthy rancher named Bart Jason is trying to drive the MacDonald family off their land by cutting off their water supply. Thornton agrees to help Hara and hires a young sharpshooter named Mississippi, played by James Caan, to assist them.
As they try to protect the MacDonalds, they also come across a feisty young woman named Joey MacDonald, played by Michele Carey, who is determined to get revenge on Bart Jason for killing her brother. The group faces several skirmishes with Jason's men, as well as internal conflicts and personal demons. Thornton, haunted by a past mistake that left him with a wounded arm and a reluctance to use his gun, must come to terms with his past and find a way to confront Jason.
Throughout the film, the group forms a tight bond and learns to trust and rely on each other. There are plenty of action-packed gunfights and intense showdowns, but the heart of the film lies in the relationships between the main characters as they face their fears and stand up for justice. In the end, Thornton must confront his old enemy in a final showdown to protect the MacDonald family and bring peace to the town of El Dorado.