Annalisse Vellum is a young woman who, together with her mother Laura Vellum, returns to Laura’s hometown after the death of her father. They rent the home of Laura’s old school classmate, Clay Roff, whose troubled teenage daughter Mary Roff disappeared years earlier. Clay invites them to dinner at his house, where they meet his current wife, Danielle Roff, and his young daughter, Heather.
Soon after moving in, Annalisse begins to endure vivid nightmares about a woman plunging from a cliff and feels haunted by the spirit of Mary. As the dreams deepen, she grows increasingly certain that something sinister lies behind Mary’s disappearance and the death of Mary’s mother, Ann Roff. The family around her grows uneasy, and suspicion falls on Annalisse herself, who is viewed as unstable by her mother, Clay, and Danielle.
Annalisse’s interest in a local man, Johnny Toussard, further unsettles the household and provokes Mary's spirit to act with renewed wrath. Against the warnings that she should stay away from him, the two pursue a fragile romance, igniting a dangerous destabilization in the already tense atmosphere. Danielle, meanwhile, convinces Laura to have Annalisse placed under temporary psychiatric observation, a move that heightens the sense of conspiracy and control within the family.
After she is released, Annalisse intensifies her investigations, uncovering troubling information about Danielle’s past: Danielle had been treating and drugging Mary and may have been involved in Mary’s death, all while having an affair with Clay, who is now married to Danielle. This cascade of secrets culminates in a supernatural confrontation as Mary’s spirit possesses Annalisse to confront Johnny and to reach out to her father’s memory. In a climactic explosion of repressed guilt, Mary’s spirit uses Annalisse to ride her beloved horse and strike a deadly blow to Danielle.
Clay’s truth comes to light as he is forced to confront the reality that Danielle murdered Ann and manipulated Mary’s mind to keep her quiet. He reveals that he had buried Mary’s body by the cliff, believing she had killed her mother, and that in a final, devastating moment he took his own life. With the web of lies unraveled, Mary’s spirit finds peace, thanking Annalisse and promising to wait for her on the other side before vanishing.
In the aftermath, Annalisse is free to forge a new path, and she eventually reconciles with Johnny, stepping into a future where the haunting is laid to rest and a fragile sense of closure has been earned.
