After the Civil War, the Dallas area of Texas is terrorized by brothers Will, Cullen and Bryant Marlow.  When they steal cattle owned by his family, Felipe Robles warns the Marlows that he has sent for a United States Marshal.  Martin Weatherby, a greenhorn from the North, is the marshal assigned to the area.  On its way to Dallas, Martin's stage stops in a town where he witnesses Wild Bill Hickock kill Blayde "Reb" Hollister, a former colonel in the Confederate army, who is now wanted by the law.  Martin soon learns that the shooting was a ruse to allow Reb, who is determined to accompany him to Dallas, to be free of prosecution.  Although Reb does not reveal this to Martin, the Marlows destroyed his family home in Georgia during the war, and he is now determined to exact revenge.

Reb changes clothes and identities with Martin, who reveals that his only reason for going to Texas is that he wanted to impress Tonia Robles, his fiancée.  When they arrive at the Robles ranch, Reb introduces Martin as his brother, and they take Tonia into their confidence.  In town, Reb, pretending to be Martin, tells Will Marlow that his enemy, Reb Hollister, is dead.  Reb then offers to buy a building in town which will be used as a town hall.  While they are talking, Bryant, wanting the money that Reb offers for the building, shoots Walters, who owns the best building in town.  Bryant's shots attract Reb, who then kills Cullen, but is wounded by Bryant.  Will acts horrified and pretends to disown his brother, while Bryant flees to a hideout.

Bryant orders his mistress, Flo, to pose as Mrs. Walters and lure Reb to the hideout.  Reb dissuades Bryant from shooting him, however, pointing out that the money for the building would not be available if he is dead and cannot remove it from the bank.  When Reb leaves the hideout, he is followed by Bryant and his men.  Reb separates Bryant from his men, and hangs him by his feet from a tree.  Then Reb publicly accuses Will of being in league with Bryant, thereby forcing him to post a reward for the capture of his brother, dead or alive.  Reb sends a copy of the wanted poster to Bryant's hideout, but while he is waiting for Bryant to come after Will, a stranger in town recognizes him.  Will overhears their conversation and runs away.  Reb manages to kill Bryant, but before he dies, he tells Reb that Will gave the order to burn Reb's house to the ground.

Reb follows Will to Fort Worth, but before he arrives, Will organizes a posse to capture Reb, who is still wanted.  While Reb is in jail, Will's men attack the Robles ranch, demanding a large sum of money from Robles.  Reb escapes from jail and heads for the ranch, followed by the posse.  The posse and Will's men shoot it out and Reb corners Will, strangling him.  When everything is over, Martin hands Reb the pardon he obtained for him.  Tonia and Reb, who have fallen in love, decide to marry, and Martin, who has lost his fiancée, announces that he will build a railroad to the now peaceful town of Dallas.