A dead body is found in the swimming pool of the "Schloss Hamberg" boarding school: Stephan appears to have committed suicide. Lovesickness may have driven the introverted son of a renowned banker and a celebrated actress to his death. However, an inconspicuous laundry button changes the entire scenario.

Klara Blum and Kai Perlmann have been a well-rehearsed team for years, working well together and also getting along privately. It is all the more dreadful when Klara finds out that Perlmann unexpectedly finds himself in the crosshairs of the investigations involved in the murder of a young woman because he had met Constanza on the evening of her death.