Jim Killian, Glenn Ford arrives at Vinegaroon, a dusty town split between cattlemen and sheep herders, and buys a vacant barn that quickly becomes a focal point in the brewing conflict. Cattle rancher Asa Beck, his son Coke Beck, and their cowhands harass the nearby sheepherders, sometimes with deadly force, pushing the two sides toward open retaliation; the town soon learns that Killian is a formidable gunfighter and is asked to work for either side, but he invites everyone to a town meeting instead. There, Killian reveals a new identity: he has become a preacher and has transformed his barn into a church. He pledges to protect all residents and declares that no one else may kill, except himself; when two of Beck's cowhands draw their weapons, Killian shoots them both to demonstrate his rule.
The following Sunday, all of Vinegaroon and the surrounding area attends Killian's church service. Killian shows that cattle and sheep can live together and share water, arguing that harmony among animals mirrors how people of different backgrounds can coexist. But Beck had suspected Killian's true threat and has hired an outsider, Mace, J.D. Cannon, to expose him. After the service, Mace publicly brands Killian as a former criminal and a murderer. Beck and his allies push to expel the preacher, but others defend him, insisting he already paid his debt to society and has earned a second chance. Bart Paterson, William Bryant the cattleman, and Abraham Murdock, James Griffith the sheepherder, decide to follow Killian's lead and seek peace between their communities.
Meanwhile, Killian takes under his protection a half-Native American girl named Leloopa, Barbara Hershey; Coke Beck becomes infatuated with her. After Killian discusses the Becks' recent destruction of Scotty Andrews' homestead with Madge McCloud, Carolyn Jones the saloon madam, Coke corners Leloopa in the stable and assaults her. Killian learns of the assault and administers a severe beating to Coke, but in full view of the town.
In response, Asa Beck begins moving his cattle to the contested watering hole to consolidate control and deny the sheepherders access. In the night, Scotty Andrews, Ed Bakey, sneaks into their camp and fatally stabs Coke with his wool shears, only to be gunned down by Mace. A grieving Beck declares war on Vinegaroon and orders Mace to burn Killian's church and kill the preacher. The conflict escalates as Mace corners Killian in the saloon and holds him at gunpoint while Beck’s men torch the church; Killian shoots his way free, outgunning Mace and scattering his followers. The church burns, but the townspeople rally to fight back, and the flames are outmatched by their determination. Madge steps in again, urging Killian to choose a path: continue as a preacher or fully embrace the gunman role.
Abashed, Killian discards his guns among the ashes of the church and asks the people to join him in protecting the sheepherders. Without weapons, the townspeople ride to the watering hole and form a human barrier between Beck's men and the targeted herd; Beck’s confidence dissolves as the unarmed crowd stands firm. Seeing the shift, Beck relents, shares a drink with Madge, and ultimately agrees to share the resources and water rather than wage war. The final moment shows Killian and Leloopa watching as cattlemen and sheepherders mingle, shake hands, and begin to live together in a fragile but hopeful peace.
