A uranium deposit brings turmoil to the small South American republic of Guatalpa. Between two revolutions, the government tries unsuccessfully to decide whether the Americans, Soviets or Cubans will exploit the concession. Delegates from these nations spy on and betray each other to achieve their goal.
Journalist Claude Leroy (Jacques Champreux) 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 (Jean Martin). An adorant of Lucifer, he aims to enslave the world. Accompanied by their acolyte, Pierrot Robichat (Gérard Zimmermann), and a young girl, Françoise Cordier (Claire Nadeau), Claude Leroy is determined to finally reveal the mysteries of the group's criminal enterprise.
Inspector Bérurier, having inherited a mansion three years earlier, comes to collect rent from the tenant when the latter is murdered under mysterious circumstances. Béru calls Commissaire San Antonio to the rescue, and the two men discover that Laurenzi's hotel is home to a "brothel" whose director, Madame Albertine, soon reveals to the two policemen that Laurenzi was having an ongoing relationship with Helga, one of the boarders, and Mr. Max, a regular guest of the house.
Adrien Chautard, a major industrialist from Abidjan, has been chosen to replace an expert on the official Ivory Coast delegation sent to Paris to discuss the country's association with the Common Market. Chautard is delighted at the prospect of this trip, where he will be reunited with the woman of his dreams: Elisabeth. Alas, at Abidjan airport, a nasty surprise awaits him: Berthe, his lawful wife, has decided to leave with him to consult a leading cardiologist in the capital.