When Texas Ranger Dave Wyatt shows up at his law office, asking for help, former Ranger Tex Haines admits that business is slow and agrees to aid Dave in investigating a range war that has been disrupting life in nearby Three Corners. Tex is particularly anxious to resolve the matter because Three Corners' sheriff Jim Whitlock, his childhood guardian, is being accused of incompetency for not ending the sheep and cattle rustling that has fueled the war. Also on the case is Ranger Panhandle Perkins, who has gone undercover as a tinker in order to spy on suspected rustler Pete Magoo. While fixing Magoo's belt at his hideout, Panhandle eavesdrops on a conversation between Magoo and general store owner Sam Taylor and his henchman, Bill Ganer. Panhandle hears Taylor, who has been orchestrating the range war so that he can eventually take control of the area, order Ganer to murder cattleman Jed Moore during a trip to Twin Falls. Panhandle immediately reports this news to Dave and Tex, but the Rangers are unable to save Moore and cannot prove that Taylor was involved. When word of Moore's murder reaches his Circle D ranch, his partner, Dick Vernon, vows revenge on sheepherder Ruth Lane, whom he assumes is behind the killing. The next day, Vernon and the Circle D cowboys attack Ruth's ranch, but the ensuing gun battle is stopped by Dave, Tex, Jim and Panhandle. After Jim arrests Vernon and his ranch hands, Tex instructs him to let Taylor know that the men are in jail. The Rangers then put Ruth and her men under house arrest at Ruth's ranch, and Panhandle is assigned to guard them. Now aware of the Circle D arrests, Taylor, meanwhile, orders Magoo to spy on Ruth's place while Ganer is cutting the Circle D fences. Dave and Tex catch Ganer making the cuts, but despite a long, furious pursuit, he outrides them both. After Dave decides to ride back toward the Circle D, Tex finally catches up with Ganer and arrests him. At Ruth's ranch, meanwhile, Panhandle hears Magoo sneaking into the house and locks Ruth and her men in a closet before the outlaw can see them. Although Panhandle tricks Magoo out of the house, Ruth and her men manage to escape and head for the jail. While Panhandle races to warn Dave about Ruth, Tex, who has deduced that Ganer outrode them using a relay of horses, threatens to abandon him if he doesn't confess all, but Ganer refuses to speak. At the same time, Dave confronts Magoo at one of the relay points, and the two begin to fight. Tex interrupts the fight, and as soon as he is arrested, Magoo implicates Taylor in the rustling. After spotting Ruth and her men on the trail to town, the Rangers then dash off for Three Corners, where a masked Taylor and his men are firing on the jail. Jim releases Vernon and the Circle D hands so they can defend themselves, and during the ensuing battle, Taylor's men set fire to the jail. Just then, however, the Rangers and Ruth's men ride up and, while Dave captures Taylor, Tex and Panhandle round up the other outlaws. Later, with the range war culprits behind bars, the Rangers bid Jim, Ruth and Vernon goodbye and head off for their next assignment.
