Based on story by Alexandre Dumas. American aviator Tom Wayne (John Wayne) and co-pilot, Stubbs (Noah Beery Jr.)are flying over an African desert when they see bandits attacking three troopers of the French Foreign Legion. Wayne quickly stops the attack and rescues Legionnaires---Clancy (Jack Mulhall), Renard (Raymond Hatton) and Dutch Schmidt (Francis X. Bushman Jr.)introduce themselves as "The Three Musketeers." They inform Wayne that the attackers were followers of "The Devil's Circle," a fanatic cult out to destroy the Foreign Legion by gun-running and insurrection. The cult's leader is El Shaitan (Yakima Canutt), a masked man whose real identity is known to none. Wayne is drawn into the fight through the encouragement of his new friends, and a call for help from an old friend, Armand Corday (Lon Chaney Jr.), who has been duped into The Devil's Circle, but is trying to break away. Helped by the Musketeers and Armand's sister, Elaine (Ruth Hall)), Wayne sets out to smash the cult.
