Journalist Claude Leroy reports that a secret society, The Companions of Baal, is behind a hold-up in the small town of Blaingirey. They are led by the Grand Maître Hubert de Mauvouloir. An adorant of Lucifer, he aims to enslave the world. Accompanied by their acolyte, Pierrot Robichat, and a young girl, Françoise Cordier, Claude Leroy is determined to finally reveal the mysteries of the group's criminal enterprise.