Natatorium.

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.