The story revolves around the Graham family, who are still reeling from the death of their matriarch, Ellen. The family consists of Annie (Toni Collette), a grief-stricken mother; her husband, Steve (Gabriel Byrne); and their two children, Charlie (Milly Shapiro) and Peter (Alex Wolff).

As the family tries to come to terms with their loss, Annie becomes increasingly obsessed with uncovering the dark secrets of their family's past. Her fixation on her mother's death and her own family history begins to unravel a disturbing and terrifying narrative.

As the story unfolds, it becomes clear that the family's ancestral history is marred by tragedy, trauma, and mental illness. Annie's own mother, Ellen, had a complicated and strained relationship with her own family, and Annie's investigation into their past only serves to exacerbate her own mental health issues.