Two paintings are stolen. Amateur private detective Roland Gautier investigates.

The local building-contractor Martin Roumagnac is fascinated by the fashionable Blanche Ferrand. To impress Blache, Martin presents her with a villa. However, this ruins him financially. Despite Martin's many efforts for the now femme-fatal Blanche, she is not able to chose between him and the rich consul De Laubry.

June 1944, a French town towards the end of the occupation. Following several attacks perpetrated by the resistance, the inhabitants who listen to English radio are rounded up by the Germans in a prison and considered as hostages. In one of the cells are found men from all walks of life: an aristocrat, the Viscount of Saint-Leu, Doctor Noblet, a resistance fighter, Béquille the wanderer with a wooden leg, and a strange character nicknamed "Black Market". The latter arouses mistrust among the prisoners, because it could well have been introduced by the enemy.