Three Foreign Legionnaires who refer to themselves in song and banter as the Three Musketeers fight renegade Arab forces under the mysterious El Shaitan. Rescued from a surrounding force by army pilot Tom Wayne, they support Wayne as he tries to uncover the identity of El Shaitan, who is smuggling guns into Algeria in hopes of creating a full-scale revolution. Only by going undercover as a member of the Devil's Circle can Wayne learn the secret of El Shaitan's identity.