Outside the snowy mountain town of Lahood, California, thugs working for big-time miner Coy LaHood ride in and destroy the camp of a group of prospectors and their families who have settled to pan for gold in nearby Carbon Canyon. While leaving, they shoot a dog belonging to 14-year-old Megan Wheeler. As Megan buries her dog in the woods and prays for a miracle, thunder rolls and a stranger rides down the slopes.
Megan's mother, Sarah, is being courted by Hull Barret. When Hull heads to town to pick up supplies, four of the thugs begin to beat him with axe staves, but he is rescued by the stranger. Hull invites him to dinner, and while the stranger is washing, Hull notices what look like six bullet wounds in his back. Shortly after, he appears wearing a clerical collar and is thereafter called "Preacher".
Coy LaHood's son Josh attempts to scare the Preacher off with a show of strength from his giant work hand, Club, who breaks a large rock in half with a single hammer blow. When Club attempts to attack the Preacher, he hits Club in the face with his hammer and delivers a blow to Club's groin, then gently helps him onto his horse. The miners now team together to smash the rest of the boulder.
Meanwhile, Coy LaHood returns from Sacramento and is furious to learn about the Preacher's arrival, saying that his presence would strengthen the resolve of the tin-panners. Failing to bribe the Preacher into settling in the town, instead, LaHood is persuaded to offer the miners $1000 per claim provided they evacuate within 24 hours. LaHood threatens to hire a corrupt marshal named Stockburn to clear them out if they refuse.
The miners initially consider accepting the offer, but when Hull reminds them of their purpose and sacrifices, they decide to stay and fight. The next morning, however, the Preacher leaves without notice and retrieves his revolver from a bank box. Meanwhile, the miners find that LaHood's men have blown up the creek running through their camp, causing it to dam up. They have a brief discussion, but agree to stay and continue mining the now drying creek bed. Megan, who has grown fond of the Preacher, goes looking for him and rides into the LaHood strip mining camp, where Josh attempts to rape her, while his cohorts look on and encourage him. At that moment, the Preacher arrives on horseback and rescues Megan, shooting Josh in the hand in the process.
Stockburn and his six deputies arrive at the town and LaHood describes the Preacher to Stockburn, who appears startled and says that he sounds like someone he once knew, but it could not be, since that man was dead. Spider Conway, a miner at the camp, recovers a large gold nugget and rides into town, where he yells drunken abuse at LaHood from the street. After gunning him down, Stockburn tells Spider's sons to tell the Preacher to meet him in town the next morning.
The following morning, the Preacher and Hull blow up LaHood's site with dynamite. To stop Hull from following him, the Preacher then scares off Hull's horse and rides into town alone. In the gunfight that follows, he kills all but two of LaHood's men, and then, one by one, all six of Stockburn's deputies as they spread through the town searching for him. When he goes face-to-face with Stockburn, the latter recognizes him in disbelief and goes for his gun. The Preacher draws first and shoots him, sending six bullets out through his back, before shooting him in the head. LaHood, watching from his office, aims a rifle at the Preacher, only to be shot and killed by Hull, who enters through a back door.
The Preacher nods at Hull and remarks, "Long walk", before galloping toward the snow-capped mountains. Megan now drives into town and shouts her love and thanks after the Preacher. Her words echo through the canyon as he rides off.