Equinox (2020)

In 1999, nine-year-old Astrid is traumatized by the mysterious disappearance of her sister Ida together with her school class, who are celebrating their graduation in a typically Danish fashion. Astrid suffers from nightmares and horrific visions following the tragedy. Twenty-one years later, when one of the survivors from the class calls her up unexpectedly, Astrid decides to investigate what happened in 1999. As she begins her exploration of the long-ago events, she discovers a dark and unsettling truth that involves her in ways she never imagined.