Sophie, the daughter of the homeland security official and incoming president of the state bureau of criminal investigation, Herbert Wichert, abruptly disappears without a trace from the elite boarding school Erlengrund. The criminal investigator Isabell Mosbach, who was in the process of dealing with her deceased mother’s estate, is instructed to work undercover in the school as a sports teacher named Karla Parker. The officer in charge of the investigation, Sellinger, is initially reluctant to work with her. Isabell omits to disclose that she had been an Erlengrund boarder for a while as a young girl, but was forced to leave under the cover of darkness when her father suddenly disappeared. Isabell soon becomes aware of the highly gifted pupil Felix, who regularly provokes his fellow students and is severely disliked by Sophie’s friend Till. Isabell learns that Sophie is pregnant and, besides her friendship with Till, appears to be in a secret relationship with an older man. On the fourth day of the undercover investigation, Felix’s lifeless body is found in a lake, the victim of an attack with a weapon that was linked to the death of two police officers in the 1980s during a demonstration against the extension of Frankfurt airport. Their killer, Volker Jens, fled abroad and later died in a traffic accident. At the time of the police murders, he had been living in a left-wing commune with Felix’s father, Frank Baumschulte. Herbert Wichert and the woman who is now his wife, Susanne, were among their circle of friends. Markus Dietze, the son of one of the murdered police officers, remains convinced that Volker Jens was not the sole perpetrator. In her mother’s estate, Isabell discovers that she had been receiving regular payments from the last 25 years from a foundation suspected of involvement in laundering assets that had gone missing from the SED, the governing political party of the former East Germany, and that the same foundation is still funding the boarding school. Her encounter with the hastily summoned chairman of the foundation, Maas, brings back painful memories of her father, who has not been seen for 25 years.
