Natatorium

18-year-old Lilja stays with her estranged grandparents in the city while she auditions for a performance group. Waiting for the result Lilja observes her grandmother's peculiar behaviours that involve weird religious rituals. When she discovers a swimming pool in the basement that plays a part in her grandmother's rituals, the girl gets even more curious about what goes on in the house. When the family, who have not met for a long time, gather to celebrate her acceptance into the group, an ugly family secret emerges, and the family gathering ends with a horrifying tragedy.