In Lincoln County, John Chisum John Wayne, a kindly and successful cattle baron, finds his peace threatened when the amoral Lawrence Murphy Ben Johnson and his business partner James Dolan forcibly buy up most of the land and businesses in the area. Initially, Chisum tries to stay out of the conflict, though he does allow ranchers driven off by Murphy to water their herds on his land, a quiet gesture that hints at his sense of fairness.
Murphy bribes Sheriff Brady Bruce Cabot to act on his behalf, secretly hiring Neemo Lloyd Battista and his band of outlaws. The gang kills two of Chisum’s men and steals a herd of horses, advancing Murphy’s monopoly and showing how easily law and order can be bent for profit. Chisum and his men pursue the thieves, recover the stolen horses, and uncover a cache of American money hidden in the pocket of the Mexican outlaw, a discovery that amplifies the stakes for everyone involved.
The trail to justice grows tangled when they are aided by Billy 'The Kid' Bonney Geoffrey Deuel, a notorious killer who has recently been given a chance to reform by Henry Tunstall Patric Knowles, Chisum’s charitable British neighbor. Billy’s arrival adds a volatile edge to the conflict, and his growing relationship with Sallie Chisum Pamela McMyler begins to unfold as the town watches the uneasy balance between reform and vengeance.
Sallie arrives in Lincoln to live with her uncle, while Alexander McSween Andrew Prine — invited by Murphy to act as his lawyer — comes with his wife Sue McSween Lynda Day George on the same stagecoach. At Sallie’s welcome party, Murphy sends Jess Evans Richard Jaeckel and his gang to rustle Chisum’s cattle, which are being driven toward a nearby army post to feed Native Americans on a reserve. A wary Pat Garrett Glenn Corbett passes through, warning Chisum’s men of the impending assault; a tense shootout erupts, one wrangler falls, and the cattle stampede disrupts the fragile order.
Chisum seeks legal redress by calling on Justice J.B. Wilson Ray Teal, but Brady refuses to pursue his own deputies when they commit murder. Wilson deputizes Chisum and Garrett, and together they recapture the fugitive deputies in a nearby town. Billy, driven by a desire for revenge and skepticism about Lincoln’s justice, knocks out Garrett, kills Morton and Baker, and rides into town to publicly murder Brady before fleeing. Murphy, manipulating politics, convinces Governor Axtell to replace Wilson with the hired bounty hunter Dan Nodeen Christopher George, a man who holds a storied grudge against Billy.
As a large posse hunts Billy, he gathers allies and launches a bold assault with Henry Tunstall’s former wranglers, Charlie Bowdre Ron Soble and Tom O’Folliard Christopher Mitchum. They break into McSween’s store to acquire dynamite for a bank heist, but Nodeen spots them, triggering a long, brutal firefight that tears through Lincoln’s streets. McSween, unarmed and weary of the bloodshed, pleads for exit, but only Sue is allowed to escape to fetch Chisum as barricades rise around the town.
In a fateful confrontation, Nodeen shoots McSween in cold blood, an act that crystallizes the town’s sense of betrayal. Chisum and his men return, driving Murphy’s cattle through the barricades to carve a path for a final stand. Billy pursues Evans and kills him, while Chisum confronts Murphy in a physical duel that ends with both men tumbling from a balcony. Murphy is fatally impaled on a decorative bull’s horn he wielded against his foes, and Nodeen departs town, leaving Billy to navigate the aftermath.
With law and order taking a different shape, Garrett becomes Lincoln’s sheriff, and Sallie’s relationship with him grows even as Governor Wallace’s forces offer amnesty to those who took part in the land war. Peace, uneasy as it is, settles over Lincoln County, and Chisum quietly surveys his land from a high hill, a steward of a landscape reshaped by ambition, loyalty, and the pursuit of justice.
