A woman is brutally murdered in front of her young daughter, the sole witness to the crime. The challenging case is assigned to Detective Huldar, who must unravel a web of perplexing clues while dealing with a traumatized child who has been rendered mute. To help unlock the girl's memories, Huldar seeks the expertise of a child psychologist-only to discover it's Freyja, a woman he recently had an awkward date with. Forced to collaborate, Freyja and Huldar must race against time to stop a killer who strikes again and remains perilously close.

The eighteen-year-old Lilja visits Áróra and Grímur, her estranged grandparents, in the city as she undergoes auditions for an international art performance group. When her father, Magnús and his younger sister Vala, two of Áróra's and Grimur's four children, find out about Lilja’s stay in the family house, a sense of panic arises. When the family gathers in the home to celebrate Lilja’s acceptance into the art group, a dark secret emerges, and soon a seemingly normal family celebration turns into a horrifying tragedy that nobody could have foreseen.