Since the sudden death of her daughter Simona, Franziska Wiesner has become a broken woman. Then one day, she is found dead in the basement of her house - her body is disfigured by bite wounds. Nils Trojan and his team are feverishly trying to find an explanation for her mysterious death when a young boy discovers another body in an abandoned gymnasium on the outskirts of Berlin. It is Simona's former best friend. Her body also bears the cruel marks. Trojan cannot yet imagine that the further investigations will lead him to the darkest abyss he has ever gazed into.