An aging cowboy faces changes in the West with the rise of civilization.

In the late 1880's Monte Walsh and Chet Rollins, two aging cowboys, ride into the town of Harmony, and manager Cal Brennan offers them a job at the Slash Y Ranch. There they meet an old friend, Shorty Austin, and the three men ride into town where Monte visits Martine Bernard, his mistress, at the local saloon, while Chet courts Mary Eagle, a widow who has inherited a hardware store. Soon after Shorty loses his job at the ranch, he becomes involved in a saloon brawl and kills a man who turns out to be a marshal. Chet, who marries Mary Eagle and settles down to work in the store, tells Monte that the day of the cowboy is gone and that he, too, should settle down. Martine, however, has moved to Charleyville to work in a more prosperous saloon. Monte follows her and proposes marriage. As he leaves Charleyville, the drunken Monte comes upon a wild horse that is part of a Wild West show and decides to tame the stallion. The owner of the show offers Monte a job, but Monte is too proud to become a carnival attraction and turns him down. He mounts the horse and destroys a large part of the town during the wild ride. Upon returning to Harmony, Monte is informed that Chet was killed by Shorty during a robbery of the hardware store. Monte sets out in pursuit of Shorty but learns that Martine is very ill. He rides to Charleyville to find Martine dead and Shorty waiting for him. The two men stalk each other throughout the town until Monte finally kills Shorty.