Mark Hudson is worried by the growing depredations of a mysterious gang of rustlers in the San Carlos Country. He learns that his friend, Sam Brice, has been warned to leave the territory. And it is Mark's resolve to save Brice and his daughter, Ellen, with whom he has fallen in love. Mark has reason to suspect that Reeve Bett, a newcomer to the town, is the arch-plotter. He also finds that the jealousy of a neighbouring rancher's daughter adds to his danger.