The story centers about a group of vigilantes organized to protect miners in the picturesque but sinister days of the California gold strike. Jim Benton (Dick Foran) and Tombstone (Buck Jones) lead their "riders", Pancho Lopez (Leo Carrillo) , Smokey (Noah Beery Jr.), Borax Bill (Guinn 'Big Boy' Williams) and Tex (Glenn Strange), in a raid on a fake Protection League, organized by crooked connivers to gain control over the biggest claims in the Panamint region. They have barely restored peace and withdrawn to the saloon to be toasted by the grateful miners when the wounded Chuckawalla Charley Morgan (Frank Austin), an old desert rat, is carried in and reveals he has traced the Lost Aztec mine...a search in which he and Benton were partners, since the latter had grub-staked him. Chuckawalla asks Benton to give his share to his niece, Mary Morgan (Jean Brooks as Jeanne Kelly), and gasps his last breath. Just then, Benton gets a tip that Wolf Reade (Charles Bickford) and his gang of death valley terrorists, including Butch (Lon Chaney Jr.) , have made to plans to rob the incoming stagecoach, which has Mary and Tombstone as passengers. Reade kills the stagecoach driver before Benton's riders arrive, and the stagecoach horses careen toward a rickety mountain bridge...and death yawns below for Mary and Tombstone. (Continued next week in Chapter Two: "Menacing Herd")