John Cannon needs cattle from Mexican ranchers for his Army beef contract, but finds the frightened men are being forced to sell at cheap prices to a ruthless cattle buyer. When John offers them higher prices, the ranchers refuse to sell because Dolf Tanner has threatened to kill them if they do. John and brother Buck try to force the ranchers to sell by refusing them watering rights, as they drive their herds toward Tanner. But Tanner strikes back by giving Apaches new rifles and urging them to kill the Cannon herds.