Texas cowboy Jim Lassiter comes to Cottonwood, Arizona to seek revenge on the man who stole his sister Millie from her husband fifteen years previously. Jim is also searching for his sister's baby, who is by now full-grown. On his way into town, Jim prevents the whipping of ranch foreman Venters by a vigilante group led by Adam Dyer and Jerry Card. Jim receives the thanks of the ranch's owner, Jane Withersteen, who nonetheless remains cool to Jim, for she has maintained an intense dislike of guns since her father was shot in the back years before. At the town's courthouse, Adam confers with his uncle, Judge Frank Dyer, the head of the vigilante committe, which has become corrupt since the death of Jane's father. Dyer has used the vigilantes to terrorize the local ranchers and acquire their land, and he now intends to do the same to Jane. Adam protests, for he desires to marry Jane and acquire her land that way, but Dyer orders his reluctant henchman, Steve Oldring, to rustle Jane's cattle that night. Although one of the herds is stolen, Jim saves the others from stampeding off a cliff, for which Jane rewards him with the high-spirted bronco "Wrangle." The next day, while Venters and Jim try to locate the missing cattle, they run into two of Oldring's confederates, Bill and a mysterious masked rider. Bill is killed during the shootout, but Jim succeeds in capturing the masked rider, who is actually a young woman. Jim and Venters take the woman, who is named Bess, up a mountain face to a secret hideout that is the only entrance to the next valley. Venters holds Bess captive there while Jim, who was wounded in the gunfight, returns to Jane. A week later, the recuperated Jim confronts Oldring, who was once a hand on the Lassiter ranch. Oldring explains that the man who stole Millie gave him her daughter Bess to raise after Millie died. He is about to reveal the man's name when he is shot by Jerry, who warns Dyer about the incident, then steals two of Jane's thoroughbreds. Jim captures Jerry, however, and forces him to reveal that Dyer is the man who stole Millie and caused her death. Jane pleads with Jim not to resort to violence, but when Dyer kidnaps her ward Fay, Jim goes into town for a showdown. Jim succeeds in rescuing Fay and killing Dyer, but he is pursued by Adam and the rest of the gang. Jim, Jane and Fay reach Bess and Venters, who have fallen in love, and give them their horses. While Bess and Venters ride off in the hope of distracting some of the gang, Jim helps Jane and Fay climb the mountain. Adam and his men follow the climbers, and with no recourse left, Jim starts an avalanche that buries their pursuers and blocks their own return to the valley. Welcoming a new life together, Jim, Jane and Fay look to the next valley and smile.