A young and idealistic attorney named Ransom Stoddard arrives in the rough town of Shinbone in the wild west to establish a law practice. He is quickly confronted by the brutal outlaw Liberty Valance, who thrives on fear and violence, maintaining a stranglehold over the region. After being savagely beaten by Valance when he attempts to bring law and order, Stoddard is rescued and tended to by the kind-hearted Hallie and her friend Tom Doniphon, a tough and respected local rancher with a strong sense of justice and his own way of dealing with the lawless.

Stoddard is determined to bring Valance to justice legally, despite the townsfolk's skepticism and his own fears. He starts to teach the local populous to read and write, aiming to educate them about democracy and the rule of law in preparation for the upcoming statehood of the territory. As Stoddard becomes more involved in the community and develops feelings for Hallie, he realizes that his legal expertise alone may not be enough to defeat Valance. Meanwhile, Doniphon, who also harbors affections for Hallie, stands as the only one seemingly capable of standing up to Valance, setting up a conflict that will test the resolve of all parties involved and challenge the foundation of their moral beliefs.