The film opens with a captivating scene, as we gaze from a workshop window toward a treehouse, then zoom into a dollhouse bedroom within the workshop. The narrative follows Steve Graham as he wakes his teenage son, Peter, and 13-year-old daughter, Charlie, in preparation for their 78-year-old grandmother Ellen Taper Leigh's funeral. Amidst this somber setting, Steve discovers Charlie still asleep in the treehouse.
At the funeral, Steve's wife, Annie, who is an artist creating miniature dioramas, delivers a poignant eulogy for her mother. During Annie's heartfelt speech, Charlie disrupts the moment by making clucking noises while sketching a peculiar drawing. Later that evening, Annie engages Charlie in a conversation about her grandmother, during which Charlie expresses a concerning thought that Ellen always wished she had a male grandchild. This revelation leaves Annie puzzled as Charlie voices her anxiety about who will look after her now that Ellen is gone. That night, Annie experiences a haunting vision of her mother while looking through a memory book in her workshop.
In a strange incident at school, a bird tragically flies into Charlie’s classroom window. Afterward, Charlie ends up outside, where she decapitates the deceased bird. Meanwhile, Annie's research on apparitions leads to more unsettling discoveries; Steve learns that Ellen's grave has been desecrated but opts not to share this disturbing news with Annie. Instead, Annie, claiming she’s going to the movies, secretly attends a grief counseling group where she opens up about her mother's struggles with mental health, including dissociative identity disorder and dementia.
As Charlie encounters inexplicable phenomena, such as a strange light in her bedroom, gallery owner Silvia Archer reaches out to Annie regarding her art pieces, including one that centers on her mother. Tension rises as Peter requests permission to attend a party where he hopes to reconnect with his classmate Bridget. Despite Annie's insistence that he invite Charlie, he ends up leaving her behind.
At the party, Peter becomes consumed by his desire for Bridget, abandoning responsibility for Charlie, who, in her innocence, ingests chocolate cake containing an allergen. As a medical emergency unfolds, Peter rushes Charlie to the hospital, but amidst a tragic accident, she is decapitated when the car collides with a utility pole after Peter swerves to avoid an animal. In the aftermath, he returns home in shock, while Annie discovers the gruesome scene of her daughter in the car.
The family navigates the painful experience of Charlie's funeral, and as grief envelops them, Steve and Peter are thrown into turmoil. Peter suffers a panic attack, and Annie's isolation deepens as she grieves in solitude. In a fateful encounter at a support group, Annie meets Joan, who connects with her through shared sorrow over lost children.
As Annie’s mental state deteriorates, she confides in Joan about a troubling incident involving her children, revealing a history marred by sleepwalking and destructive visions. As Annie grapples with sleepwalking episodes, she constructs a harrowing diorama of Charlie’s death, intensifying tensions within the family as accusations surface.
Amidst swirling emotions and supernatural occurrences, Joan introduces Annie to the concept of a séance, claiming to have harnessed the power to communicate with the dead. Following this eerie experience, Annie becomes obsessed with the idea of reaching out to Charlie, ultimately leading to her own devastating sleepwalking incident, which nearly ends in catastrophe.
As the narrative spirals deeper into horror, Annie’s actions summon dark entities threatening her family. The discovery of a disturbing symbol linked to the demon Paimon connects the family's tragedies to a sinister legacy, unveiling the horrifying truth surrounding their lineage and the covenant made generations ago. Annie's desperate attempts to rectify the past lead to a series of shocking revelations, culminating in a frenzy of violence and otherworldly possession.
The film takes a climactic turn as Peter contemplates his fate in the shadow of dark forces. From confronting his own reality to the horrifying family secret, he ultimately finds himself drawn into a malevolent web spun by grief, despair, and unspeakable horror. The chilling conclusion sees Peter emerge amidst a coven of devil-worshipers, accepting a fate intertwined with Paimon, as the lineage’s curse fully manifests, leaving viewers with a haunting image of loss and the relentless grip of evil.
