Marlène asks for Laurence's help on a case involving her sister Solange, who runs a boarding house where a young woman dropped dead of poisoning.

April receives a marriage proposal from Emile Deboucke, an older rich spinning mills owner. Her engagement is not a bed of roses, and soon she has to deal with a series of murders.

April's ex-husband is accused of murder. She discovers him hiding in her apartment, and doesn't turn him to the police.

Marlène is puzzled by an ad in the paper for a "murdered party". Laurence believes it's a joke, but at set time, a man interrupts the party violently and drops dead.