The lover of a policeman is strangled in his house.

Bente, a school dropout, was a foster child on the Strand family's remote farm. Forensic medicine finds a key in Bente's stomach. Where was the girl going with two cans of gasoline? Why did the local gas station attendant sell her gasoline even though it was known that she was an arsonist? Which lock does this key fit into? Local policeman Lars Klapproth might be able to contribute to solving the case, but he does not. Because Lars is the father of Maria's missing daughter Matilde. He had made the toddler disappear with the help of GDR state agencies during the reunification period. When Maria, who had fled the republic, returned to get her daughter shortly after the fall of the Berlin Wall, Matilde had already been adopted and could not be found.

At the bottom of a lake, the police find a car with a wax corpse in the trunk. It is 15-year-old boarding school student Alex, who has been missing for five years. With the sad certainty that she has been murdered, the case, which should have been closed, takes a completely new turn. Her teacher, the charismatic Hajo Rick, convicted of her murder on the basis of circumstantial evidence and witness statements, could be innocent after all! When the ambitious defence lawyer Sophia Dreyer obtains a retrial, the former investigator finds himself in trouble: Chief Inspector Kai Matzen now has to throw the certainties of the past overboard - and realize that he is more personally involved than he would like. Sophia also suspects that she can't trust anyone. And what if it was Hajo Rick after all? Dreyer and Matzen investigate independently of each other, each in their own interest, and reconstruct Alex's last hours. In the process, they uncover an intrigue.