Louise Lépine finds an unlikely ally in her attempts to persuade her father to postpone his retirement, Jouin and Cochefert hear testimony from the mother of Paul Cetinet, and Fiersi, now a free agent, talks to one of the maids at Château de Bagatelle.

Guichard falls into the trap when he is lured to Château de Bagatelle by a phone call from Fiersi's son, Julien. And Commissioner Lépine confronts Fondari, the head of the vice squad.