Chatelard, one of Viscount de Kerlec's guests, has died in mysterious conditions. The police initiates an investigation and sends detective-inspector Pauc to de Kerlec's manor. Pauc decides to mingle with the viscount's guests , who are all likely to have committed the murder. Among them, there is Jacques Mauclerc, a naval officer, and a seedy character named Bartoli, in fact a spy in search of secret documents. Pauc will end up untangling the web during a dramatic séance.

After the exodus, a woman with a tidy life decides to take in the abandoned children; she meets a singer who knows how to make her see life with more poetry.

During the Second World War, Georges Masse undergoes a dangerous mission by taking secret documents from Tangiers to London.

A mysterious figure signing himself "The Ferret" keeps sending letters to the police, tipping them off about murders that are to be committed around Paris. Among those caught up in the police manhunt is a fraudulent clairvoyant.