Willy, the son of baron Van Hergershuizen, finds himself disinherited after he marries an untitled girl. His wife decides to take action and applies for the job of the baron's housekeeper.
Janus Fortuin is a goodhearted piano tuner married to a greedy landlady. Their daughter Polly is engaged to young songwriter George van Reen. When rich uncle Barend from Batavia makes a surprise visit — pretending to be a lodger called 'Van Santen' — the Fortuin family finds their lives turned upside down.
When Erica Maerlant is shot dead during a secret dance rehearsal at her luxurious villa, the Maerlant household turns out to be a serpent's nest of intrigue where everyone has a motive for the murder.
