Assuming the identity of a Ranger he finds dying on the trail, Jack Rankin, aided by his sidekick Manny, begins to clean up the lawless town of Brimstone, which is being preyed upon by outlaws robbing the nearby gold mines of the bullion shipments, secretly led by Frank Mason and his chief henchman Trigger. He is uncovered by the arrival of the dead man's sister, Marian Adams and is accused of killing the Ranger.