In the sweltering heat of the Oklahoma Territory in 1889, former lawman Jed Cooper (Bruce Dern) finds himself confronted by a formidable group of nine men led by the relentless Captain Wilson. The posse demands proof of ownership for the cattle Cooper is herding, but it soon becomes apparent that the ruthless cattle dealer has committed a heinous crime: the murder of the rancher on whose land they trespass. Despite Cooper's vehement claims of innocence, only one of the men, Jenkins (Pat Hingle), expresses any doubt regarding his guilt. As tensions rise, the men strip Cooper of his horse and saddle, leaving him utterly defenseless against their violent onslaught. Ultimately, they hang him from a tree, leaving him for dead.
By a stroke of fate, he is discovered by Marshal Dave Bliss (Ben Johnson), who manages to revive him and bring him to Fort Grant. There, the territorial judge, Adam Fenton (Clint Eastwood), clears him of any wrongdoing. Rehabilitating his reputation, Fenton offers Cooper a chance at redemption by taking on the mantle of marshal, cautioning him against seeking vengeance for the wrongs committed against him. Instead, Fenton implores Cooper to pursue justice through legal channels.
As Cooper adapts to this new role, he encounters a haunting reminder of his past—a horse and saddle outside a local saloon. His quest for justice leads him back to Reno, an original member of the posse, who meets his demise at the hands of the very marshal marked by the same hanging scar that now symbolizes Cooper's struggle. Witnessing Reno's death leaves Jenkins shaken, prompting him to surrender and disclose the identities of the remaining posse members. Cooper then pursues Stone in Red Creek, successfully apprehending him and securing his imprisonment with the help of local sheriff Ray Calhoun (Inger Stevens).
As Cooper continues to hunt down the remaining criminals, he stumbles upon a shocking crime scene—two men have been brutally slain, and their herd stolen. Rallying his own posse, Cooper embarks on a daring mission to reclaim the stolen livestock, only to find that Miller and the two teenage brothers, Ben and Billy Joe, are responsible for the theft. In a twist of justice, Cooper prevents a mob from lynching the rustlers, inadvertently leaving himself isolated and disillusioned with the very system he seeks to uphold.
Upon returning to Fort Grant with Miller and the brothers, Cooper faces a harrowing decision. Judge Fenton's draconian sentence of hanging for all three forces Cooper to grapple with the moral implications of his role as a marshal. Fenton warns that without punishment for rustlers, the public will take matters into their own hands, jeopardizing Oklahoma's quest for statehood. As sheriff Calhoun proposes an unexpected deal—payback for the lost cattle in exchange for cash from Captain Wilson and his men—Cooper's determination remains steadfast. He vows to bring all the culprits to justice, regardless of the personal cost.
The narrative culminates in a suspenseful public hanging where Cooper aims to quell the mob’s tyranny once and for all. Just as the nooses tighten around Miller and the Joe brothers, Wilson and his henchmen launch a surprise assault on Cooper in a nearby brothel, leaving him severely injured.
In his recovery, Cooper is nurtured back to health by the compassionate widow Rachel Warren. This bond blossoms into a romance, kindled by Rachel's own quest for retribution against the perpetrators who ravaged her past. Their relationship proves to be a source of comfort for Cooper, who finds solace amid the turmoil, but it also forces him to question his responsibilities as a marshal.
As Cooper regains his vigor, Judge Fenton informs him that Wilson, Tommy, and Loomis have taken refuge at the outlaws' ranch. The trio plots an ambush against Cooper, but, once again, the astute lawman prevails. In the ensuing conflict, Cooper swiftly dispatches Loomis and sends Tommy fleeing, though he ultimately fails to capture Wilson, who meets a ferocious end at his own hands.
Having accomplished his duties as marshal, Cooper returns to Fort Grant to resign his badge, rejecting Judge Fenton's corruption and demanding a pardon for Jenkins, the repentant outlaw. Fenton denies the request, citing the territory's absence of proper courts, yet Cooper's relentless spirit compels him to reclaim his badge, armed with new warrants for Blackfoot and Maddow. As he departs, Fenton's parting words resonate ominously in the air: >"The law still wants 'em."
