Volatile young gunfighter Billy the Kid (Paul Newman) works for kindly rancher Tunstall (Colin Keith-Johnston), and they develop an unbreakable bond. When Tunstall is murdered by a corrupt lawman and his cronies, a distraught Billy goes on a violent rampage through the New Mexico Territory. Billy finally guns down all the men who killed Tunstall -- but in the process he endangers the life of his old cohort, Pat Garrett (John Dehner), who doesn't take kindly to the Kid's erratic behavior.