Griff Bonnell and his two brothers, Wes and Chico, arrive in a small Arizona town. He is a reformed gunslinger who now works for the Attorney General's office, looking to arrest Howard Swain for mail robbery.
Swain is one of the landowner Jessica Drummond's 40 hired guns. She runs the territory with an iron fist, terrorizing and trashing the town with her brother, Brockie Drummond, and his boys. Brockie is an arrogant drunk and bully, but he goes too far by shooting Marshal Chisolm in cold blood. Griff intervenes and knocks out Brockie with his pistol.
Wes falls in love with Louvenie Spanger, so he decides to settle down and become the town's sheriff. Griff becomes romantically involved with Jessica after she is dragged by a horse during a cyclone.
Two of her guns, Logan and Savage, attempt an ambush of Griff in an alley. He is saved by his youngest brother, Chico, who was supposed to be leaving for California for a new life on a farm. Chico's shot kills Savage, after which Jessica's brother and hired guns try to turn the town against the Bonnell brothers.
On his wedding day, Wes is gunned down. Brockie is jailed for the murder. He tries to escape by using his sister as a shield, daring Griff to shoot, and is shocked when Griff does exactly that. Griff's expertly placed bullet merely wounds Jessica, and the cowardly Brockie then becomes the first man Griff has had to kill in 10 years.
Chico remains behind to take the sheriff's job. Griff rides out, certain that Jessica hates him for killing her brother, but she runs after his buckboard and together they ride off.
