The discovery of a dead person in a desolate residential area was reported anonymously in the early hours of the morning. Jana Gruber was overpowered in her house and brutally killed. Evidence indicates that the woman worked as a prostitute - and that she had a child. But the children's room is deserted, there is no trace of the child, a ten-year-old son. The anonymous caller is identified and, amazingly, there is a file about him: Gustav Langer used to get in touch with the law more oftenConflict. And as a suitor, he had known the victim for a long time. But is he also the murderer of Jana? Very soon they recognize similarities between the current case and an unsolved murder some time ago. Investigators are deeply alarmed by the possibility of a serial killer acting according to plan. The detectives are pushed to the limit, they investigate to the point of exhaustion against time and a psychopathic insane killer.