A summery day on Lake Chiemsee: children discover the body of a man on a sailboat. Inspector Hattinger (Michael Fitz) and his colleagues from the Prien police take up the investigation. Shortly afterwards, a second body is found: Author Annette Kaufmann (Ursula Karven) has been murdered in her vacation apartment.
It is a serial murder, the perpetrator seems to know Inspector Hattinger personally and provokes him with bloody clues. There has been a fateful connection between the two murder victims for decades: Both are complicit in the death of a young girl who lost her life due to a medical malpractice. At the time, no one was held accountable – today, everything points to vigilante justice. The focus is on the girl’s father – Albrecht Ostermeier (Edgar Selge) has been living inconspicuously in the commissioner’s neighborhood for years.
Hattinger gets closer and closer to the truth, without suspecting that he is putting himself – and above all his own young daughter Lena (Hanna Plaß) – in mortal danger. For once under suspicion, Ostermeier will stop at nothing.