The serial killer's motive is revealed, and the investigation culminates in a final race against time. Hildur gains new information about the fate of her sisters.

New evidence points to a hidden family history that connects the victims. Florian's secrets begin to emerge. Hildur and Jakob make a discovery that finally seems to explain what happened to Hildur's sisters.

While Hildur searches for answers in Reykjavík, events back home in the Westfjords take a worrying turn. The past and the present begin to intertwine.

A second murder takes the investigation to Reykjavík, and the signatures left by the perpetrator link the cases together. Pressure mounts both in the investigation and in the personal lives of Hildur and Jakob.

Hildur investigates how the murderer managed to escape, and a car linked to the case becomes central to the investigation. The murder inquiry brings Hildur's dark past to the surface as secrets regarding her sisters' disappearance begin to be revealed.

A body is discovered under an avalanche in the Westfjords of Iceland, and detective Hildur Rúnarsdóttir begins investigating an extraordinary murder. Hildur's investigative team is joined by Finnish police trainee Jakob Johanson and German trainee Florian Herrmann.