Questions arise when Senator Stoddard attends the funeral of a local man named Tom Doniphon in a small Western town. Flashing back, we learn Doniphon saved Stoddard, then a lawyer, when he was roughed up by a crew of outlaws terrorizing the town, led by Liberty Valance. As the territory's safety hung in the balance, Doniphon and Stoddard, two of the only people standing up to him, proved to be very important, but different, foes to Valance.
The murder of her father sends a teenage tomboy on a mission of 'justice', which involves avenging her father's death. She recruits a tough old marshal, 'Rooster' Cogburn because he has 'true grit', and a reputation of getting the job done.
While passing through the town of Bannock, a bunch of drunken cattlemen go overboard with their celebrating and accidentally kill an old man with a stray shot. They return home to Sabbath unaware of his death. Bannock lawman Jered Maddox later arrives there to arrest everyone involved on a charge of murder. Sabbath is run by land baron Vince Bronson, a benevolent despot, who, upon hearing of the death, offers restitution for the incident.
Blaise Starrett is a rancher at odds with homesteaders when outlaws hold up the small town. The outlaws are held in check only by their notorious leader, but he is diagnosed with a fatal wound and the town is a powder keg waiting to blow.