One year after the outbreak of a violent eruption of the subglacial volcano Katla, the peace and tranquility in the small town of Vík has been dramatically disturbed with the eruption still active. The ice near the volcano has been melting, the area has been evacuated and only a few remaining people manage to provide the necessary community service in the village, which is now only accessible by crossing the Markarfljót river.
The grand area has turned out to be somewhat apocalyptic and Vík is declared a danger zone. Mysterious elements, that have been deeply frozen into the glacier from prehistoric times, start to emerge from the melting ice with consequences no one could ever have foreseen.
A troubled police officer is forced back to her hometown. Confronting her abusive mother is inescapable but the discovery of a body changes everything. She's forced to search for a dangerous serial killer while stuck in a dark pit.
A police investigator named Arnar travels from Denmark to assist in the investigation surrounding Iceland's first serial killer. He works with Kata, the officer in charge of the case, and together they must race against the clock to find the murderer before it's too late. While the victims initially seem unrelated, the trail leads them to an abandoned boys' home named Valhalla, where some horrifying events occurred 35 years earlier.