An army captain comes to North Fork to kill the man who shot down his son in a gunfight - Lucas McCain.
The new schoolmaster's harsh stern manner causes Mark & his friend, Billy to play hooky, resulting in Mark's becoming trapped in an abandoned mine when the ceiling collapses.
A conman places bets on a vulnerable mentally-slow young man with a talent for shooting, then attempts to manipulate him into a gunfight with Lucas by telling him Lucas has been making fun of him.
A deathbed request from an old friend & neighboring rancher sends Lucas to a neighboring town to bring back the man's new wife of two weeks that he barely knows.
Lucas agrees to take a job as a federal undercover agent and goes to Wyoming to investigate rumors of sales of arms to renegade Indians. His life is endagered by the town drunk who stumbles onto his true identity and purpose.
Lucas is cursed for death by a Mescalaro witch doctor: he was foreman of a jury that convicted an Apache.