Hereditary is a psychological horror film that delves into the tragic and terrifying unraveling of a family after the death of their secretive matriarch, Ellen Graham (played by a cameo role by an uncredited actress). The story centers around Annie Graham (Toni Collette), a mother and artist, who, along with her husband Steve (Gabriel Byrne), is struggling to cope with the loss of her own mother. Annie begins to unravel strange and disturbing truths about her family’s past, and the eerie inheritance that seems to pass down through generations.

The film begins with the death of Ellen, the family matriarch, who had lived a mysterious life, rarely speaking about her past. Her passing seems to open the door to disturbing and supernatural events. Annie, already dealing with the grief of her mother’s death, is forced to confront the disturbing secrets Ellen left behind. As Annie tries to piece together her mother’s life and its impact on her family, she becomes increasingly obsessed with uncovering the truth, despite the growing terror that surrounds her.

Annie’s teenage son, Peter (Alex Wolff), becomes deeply affected by a tragedy that occurs soon after Ellen’s funeral, which forces him to question his role in the family’s fate. His behavior grows erratic, as he becomes haunted by unexplainable visions and supernatural occurrences. Meanwhile, Annie’s daughter Charlie (Milly Shapiro), who has a strange and eerie presence, appears to be drawn to mysterious figures and begins exhibiting unsettling behavior. As tensions rise, the Graham family is torn apart, and the dark forces haunting them seem to have a will of their own.