A summer's day on Lake Chiemsee: children discover the body of a man on a sailing boat. Inspector Hattinger and his colleagues from the Prien police start investigating. Shortly afterwards, a second body is found: The author Annette Kaufmann 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 partly to blame for the death of a young girl who lost her life due to a doctor's blunder.