An older woman is found dead in Valhöll's teenage home and seems to have been the same killer. The police have no idea of ​​the reasons for the killings or who is behind them.

When it turns out that Valhall's last employee is still alive, Kata and Arnar fear that the serial killer will find him ahead of them. At the same time, the police delve deeper into the shadowy history of the adolescent home and the boys who were there.