Strange things are happening in the small town of Breuil-le-Château. Provisions from the black market are stolen regularly and wealthy young men, including the squire's son, start vanishing... Ransom demands are sent but with an illegible signature. The investigation is trusted to Ducreux, the local police brigadier. He is assisted by Carlier, a film director in search of locations for his next movie, who has been mistaken for a police inspector from Paris. The two men will have more than their share of surprises.