Johnny (Marlon Brando) and his motorcycle gang roll into Carbonville for a biker competition and raise enough hell to get kicked out of town. They repair to nearby Wrightsville and continue their reign of terror. The local sheriff (Robert Keith) is helpless to stop them, but when a rival gang arrives, he manages to arrest their leader, Chino (Lee Marvin). Meanwhile, Johnny finds himself attracted to the sheriff's daughter, Kathie (Mary Murphy), and decides to stick around.