In 1870, gunslinger Buck Duane goes to the town of Welleston, Texas, where his father was murdered on the eve of his re-election as sheriff. Suspecting that Red Morgan, the new sheriff, was involved, Buck talks to him and is forced to shoot one of Morgan's henchmen in self-defense when Morgan signals to the man to shoot Buck in the back. After escaping from Morgan's posse, Buck meets Luke Stevens, a grizzled old outlaw who takes him under his wing. Luke tells Buck that they will go to Rimrock, a notorious hangout, and collect Luke's timid partner, Euchre. Luke warns Buck that because he has now been branded an outlaw, he will be blamed for many crimes he did not commit. When Luke goes to a nearby town for food, he is wounded and captured by the Texas Rangers, lead by Major McNeil and Captain Laramie. Buck rescues Luke, but the old man dies after telling him that Rimrock is run by Jim Bland's gang, under orders from a mysterious boss named Cheseldine. Buck travels to Rimrock, where he meets Euchre, who runs a general store, and saloon owner Kate. Buck tangles with Bull Lossomer, Bland's right-hand man, and further raises the gang's ire when he rescues Nancy Bowdry from them. Nancy had been kidnapped by Bland after the gang killed her father and burned their ranch. Buck, who was Nancy's childhood sweetheart, sends her to his grandfather Tom for safekeeping, and then goes to the town of Huntsville, where he has been falsely accused of killing a woman. Upon questioning the dead woman's child, sheriff Frank Taylor finds that Buck is not the murderer, and Major McNeil offers Buck a conditional pardon whereby he will be cleared of the charge of killing Morgan's henchman if he helps capture Cheseldine. Buck agrees and, after returning to Rimrock, tells Kate, who is the link between Cheseldine and Bland, that he wants to join the gang. Kate reveals that the gang will be holding up a bank the next day, and Buck passes on the information to Laramie, whom McNeil had detailed to help him. Bland receives orders from Cheseldine to set up Buck, and despite a warning from Kate, who is falling in love with Buck, he goes to the bank. Sheriff Taylor almost captures Buck, and he is wounded as he escapes. When he returns to the saloon, Buck finds a distraught Kate, who believes that he has been killed. Kate swears that she did not know of the ambush, and then, while saving Buck from being shot in the back by Cheseldine, is killed herself. Laramie is revealed to be Cheseldine, and soon the entire gang is rounded up. McNeil then makes Buck a deputy ranger and orders him to bring in Morgan. As Buck and Euchre ride to Wellestown, Euchre tells him that Nancy is going to cooking school in Kansas City and will return soon.