On the 1880s Wyoming frontier, infamous gambler and gunslinger Tom Early returns to the town in which he left his wife and young boy years before. After Early enters the general store, owner Sam Wainscott, a handicapped man, overcharges him, then jealously berates his clerk Jo for flirting with the known criminal. When Early reaches the family ranch, his 17-year-old son Tom, Jr. shows him his mother's grave and blames him for her death. Early tries to explain that his villainous reputation is unwarranted and that his intentions was to win a fortune for his wife, but the hostile boy refuses to forgive Early for leaving them. The next morning, when Early comes to the store and asks Jo to help him find a housekeeper, Wainscott insinuates that she would consider taking the job in order to have an affair with the criminal. Just then, three strangers tell a gathering crowd that they plan to drive 20,000 cattle through the town's valley on the way to market. Early recognizes ruthless businessman Grimsell among the men and protests that the farmers, as landowners, have the right to refuse access to their valley, but Grimsell claims an Indian treaty has granted him the right to drive his herd through the valley. Despite Grimsell's orders to avoid violence, his cohort Blondie recognizes Early and challenges him to draw. Early tries to refuse the challenge, but Blondie is insistent, forcing Early to kill him. Back in the store, Wainscott taunts Jo, asking her if she prefers a murderer to a "crippled man." Later that night, Jo, frustrated by Wainscott's tirades, rides to the ranch to accept the housekeeping job. When Tom refuses to believe that Early killed Blondie in self-defense, Jo, having witnessed the shooting, assures him that his father acted within the law. The next morning, Early, Jo and Tom ride to church, where the good-natured preacher, an old friend of Early's, warmly greets them; however, when Wainscott rants about Early's lawlessness, the congregation ostracizes them. Days later, after the preacher tells Early about a town meeting that has been called to discuss Grimsell, Early warns him that Grimsell will not settle the dispute legally. Jo, believing the preacher was at the ranch to accuse her of indecency, begs to know what they talked about. Early assures her that her behavior, far from being shameful, has made him happy to be at the ranch again. The next day, Grimsell offers to buy Early's land at an inflated cost to use as a shortcut to the market, but Early refuses. That evening, when young Tom kisses Jo and then apologizes, Jo agrees not to tell Early, knowing the boy acted out of loneliness and confusion. At a town meeting, after it is decided to send townsman Martin to Laramie to obtain land ownership documents to dispute Grimsell's right to drive the herd through their valley, Early warns that Grimsell will use the extra time to gather more gunmen. Later that night, Tom mistakenly assumes Early and Jo are laughing about his amorous attempt and slaps his father. When the temperamental boy refuses to apologize, Early saddles up his horse to leave. Assuming he is leaving for good, Jo rushes out to stop him, but Early assures her he will be back and kisses her. After discovering Martin's dead body in the pass the next morning, Early finds Grimsell and suggests that he take the barren route through public land nearby. Grimsell, who wants to fatten the cattle on the town's lush valley, announces that he now has 30 more gunmen to guarantee his safe passage. When Martin's horse returns to the church without its rider, the preacher gathers a posse and rides out to the ranch to enlist Early in their fight against Grimsell. Finding only Tom, the preacher allows the eager but inexperienced boy to join them. When Early returns to town with Martin's body, he learns that the posse has already left. Gathering red ribbon from the store, he rushes to the pass. The posse is soon cornered in a canyon, where Grimsell's men ambush them. Early arrives to find Tom and the preacher among the wounded. Early bandages his son's injuries then says his farewell to the dying preacher, who asks him to take care of young Tom. After leaving Tom at home with Jo, Early returns to the pass, where he plants dynamite along the cliffs, marking it with ribbon. When Grimsell and his men move the herd through the pass the next morning, Early shoots the dynamite causing it to ignite and send an avalanche of rocks to block the pass. The panicked herd stampede in retreat, killing many of Grimsell's men. Grimsell and his henchman Gunn ride to Early's ranch seeking revenge and take Tom and Jo hostage. As Early approaches the house, Grimsell and Gunn threaten to kill Tom unless Early drops his gun. Early concedes to the demand and walks towards them with his hands up, but then grabs Grimsell's gun. Unarmed and desperate, Gunn then challenges Early to a fistfight. Tom uses Grimsell's weapon to hold Grimsell at gunpoint, while Early and Gunn fight, but when Gunn reaches for Early's gun on the ground, Tom shoots and kills him. After Early orders Grimsell off the property, Tom calls Early "Dad" and admits that violence is sometimes necessary. Heartened by the boy's understanding and his triumph, Early kisses Jo and they promise each other to stay on the ranch.
