The latest case of the Hamburg Criminal Police Office suddenly hits Jan Casstorff personally: 45-year-old Karin Freiberg is found murdered in her "work apartment"; she had offered so-called "housewife sex" - prostitution without any connection to the milieu. To the surprise of his colleagues, Casstorff knew the woman because he had had a short but intense love affair with her many years ago. After that he never saw her again. Struck by the sight of the badly battered corpse, Casstorff first examines the family background of the dead. He meets her husband Joachim Freiberg, who is in a wheelchair, and their twelve-year-old son Felix.
With her employment as a prostitute, Karin - with the knowledge of her husband - financed the family's life after the former car salesman was no longer able to work after an accident. Holicek is investigating at the same time in the vicinity of the work apartment: with the exception of the caretaker Kowalski, the tenants are shocked, but make no secret of their open rejection of this trade in their house. The result of the pathology shows that Karin Freiberg was not strangled, as initially suspected, but suffocated painfully - under the blanket that lay on her body. The investigations quickly bring up further concrete information: Karin shared the apartment with a colleague Christiane, for whom she stood in on the day in question.
Was Christiane supposed to die? She stubbornly refuses to say anything about the case, even when she is beaten up by two brutal extortionists. Casstorff and Holicek can establish this quickly, but have no proof. Out of necessity, Casstorff makes a deal with them and uses their contacts in the scene. It is their information about clients who like brutal bondage variants that lead to Philipp Kochbeck being caught in the net. Kochbeck, suffering from his tendencies, admits to having tied up Karin Freiberg for his games against her will, but denies the murder. Further trace comparisons lead back to the environment of individual residents who had far more contact with the two prostitutes than initially admitted.
In this way, Casstorff gets ever deeper into the world of relationships that surrounded Karin Freiberg, and supported by an understanding Wanda Wilhelmi, he succeeds in clarifying the tragic context of the case.