Profiteer Alexander Stiles lays claim to a million acres of range in the Pecos River country, but a rancher named Claybor stands in his way as he has already claimed the water-rich location of Sweetwater as his own, and refuses Stiles' $1000 offer for his land. Led by the murderous Ash, the hired guns of Stiles kill Clayborn and his wife but their young son John survives and joins his grandfather in Austin. As the boy grows into a man he learns the use of a law book as well as a six gun, intending to use both to bring Stiles to justice. As lawyer John Clay, he travels to the Cottonwood headquarters of Stiles, self-proclaimed King of the Pecos, and meets Hank Matthews and Josh Billings, two cattlemen thrown into poverty through the crooked dealings of Stiles. John serves a summons for Stiles to appear in court but the circuit judge is too frightened to face the might of Stiles. John sends Hank to round up other impoverished cattlemen, and they provide the judge with an armed escort to Cottonwood. The judge upholds the ranchers' pleas for use of water and grass, and Stiles sees most of his ill-gotten gains turned over to public domain for proper filing. Stiles convinces newcomers Eli Jackson and his daughter Belle that John is trying to cheat the ranchers and file claims for himself. He also plans an ambush for those riding through the canyon to file claims and he sends Ash and his gunmen to the hills, instructing them to shoot anyone without the white arm bands he has supplied to his own riders. John discovers the plot and has the ranchers to also wear white arm bands, ensuring their safe passage. With their claim successfully filed the ranchers plan a cattle drive to Abilene where the railroad is promising $20 a head. Stiles steals whatever cattle he can and moves his outlaws to Sweetwater, where he hopes to extort money for use of the water there from the trail drivers. When the drive reaches Sweetwater, John confronts Stiles, revealing that he is the son of the murdered Clayborn's and that Sweetwater rightfully belongs to him. Following a siege by John and the ranchers, Stiles tries to escape by buckboard, but when the wagon tips over he is crushed by the safe containing money he has stolen from others. John pursues Ash into the rocks, offering him a chance to draw first and then ills him. John leaves his gun and his quest for revenge at the site and turns his mind to Belle and his law career.