Cashier Maurice Legrand is married to Adele, a terror. By chance, he meets Lucienne, "Lulu", and make her his mistress. He thinks he finally met love, but Lulu is nothing but a streetwalker, in love with Dede, her pimp. She only accepts Legrand to satisfy Dede's needs of money.
Zou Zou tries to help her childhood friend prove his innocence after he's accused of murder.
The Marquise de Langrune invites her friends at her castle in Beaulieu. Among them is Lord Beltham who also came to bring her a significant sum of money. The mysterious Fantômas kills the Marquise during the night. Inspector Juve is sent on his trail.
