A routine procedure suddenly turns into a murder case. The animal that was seen floating in Lake Constance turns out to be a corpse in a fur costume with a carved wooden mask. Achim Tilger, the dead man, has had an unprecedented business downfall and is closely connected to Gregor Dachser, Julia's uncle, and his ex-wife Nadine Löwenstein through the carnival club "Die Teufelskerle". To the outside world, the carnival club presents itself as a happy family. It is thanks to Pirmin's accuracy that an obscure property sale is uncovered, for which Nadine Löwenstein, as chairwoman, had to sign and which favored her friend Achim Tilger. Case solved? Not quite. Meanwhile, Mechthild Fehrenbach is researching the family tree at home and infects her daughter Nele with it. But they are not at all happy with the result: the Fehrenbachs were not nobles. On the contrary.