General Bierbeau sends his weakling son Pierre to French Morocco to fight Arab insurgents (the "Riffs") in the hopes that this will toughen him up. Pierre soon becomes the Riffs' leader and assumes a secret identity: "The Red Shadow." Pierre is still regarded as a weakling by the French troops because he always seems to let the Red Shadow slip through his fingers. When Pierre's sweetheart Margot visits the French garrison, she succumbs to the Red Shadow's charms.