After Ellie Stocker and Gedeon Winter become bitter opponents at the end of the second season, events bring them together one last time. A series of mysterious murders on both sides of the border rocks the region. While a crime pattern became apparent in the case of the Krampus murderer and Alexander Gössen, the motives for this series of murders initially remain in the dark for the investigators.

The case pushes Ellie and Gedeon to their limits and confronts them with their own story. Because while Gedeon is looking for the tormentor from his childhood, Elli tries against all odds to convict Gedeon of corruption in order to bring the truth about the murder of her colleague Yela Antic to light.