In the year 1971, Carolyn and Roger Perron, along with their five daughters, move into a run-down old farmhouse located in Harrisville, Rhode Island. As they settle into their new home, one notable oddity arises: their dog refuses to enter the house. That very night, while the kids are engrossed in a game of hide-and-clap, one of the daughters stumbles upon a boarded-up cellar entrance. Following Roger's inspection of the basement using a match, the family retires for the evening. Carolyn can't shake off her unease as the dog barks frantically outside, and one daughter feels a disturbing tugging at her feet.
Upon waking the next day, Carolyn discovers an unexplained bruise on her body, and the family is devastated to find their dog, Sadie, dead. In the subsequent days, a series of bizarre paranormal events unfold—doors creak open and shut on their own, and Carolyn hears disembodied clapping. Disturbingly, their younger daughter Cindy sleepwalks, wandering into her older sister's bedroom and banging her head against an old wardrobe. The situation reaches a terrifying climax when an evil spirit, resembling an elderly woman, attacks the eldest daughter.
Desperate for help, Carolyn turns to Ed and Lorraine Warren, renowned paranormal investigators. Lorraine recounts sensing a malevolent spirit that has latched onto the Perrons. Following an initial investigation, they inform the family that an exorcism may be necessary, but further evidence and authorization from the Catholic Church is a prerequisite. As they delve into the house's shadowy past, Ed and Lorraine uncover a chilling connection to Bathsheba, an accused witch. The haunting history reveals that Bathsheba had made a sinister pact before ending her life after sacrificing her infant, vowing to curse all who dare to inhabit her land. This discovery is compounded by multiple reports of murders and suicides tied to the property.
Determined to verify the presence of Bathsheba's spirit, Ed and Lorraine enlist the assistance of a police officer and another paranormal investigator, Drew. They set up thermal cameras and alarms throughout the house to catch evidence of the haunting. The first night yields little activity, and the clocks fail to stop at the witching hour of 3:07 AM. Over breakfast the next day, Roger expresses his gratitude towards Ed, while Ed reveals the toll that each exorcism takes on Lorraine.
However, when darkness descends once more, horrific events unfold as Cindy once again sleepwalks. The thermal cameras capture a sharp temperature drop surrounding her as she ventures into the wardrobe. Suddenly, the door slams shut. When they manage to breach the door, a secret passage is revealed, leading to the cellar where Lorraine encounters the tormented spirits Bathsheba has claimed. It becomes alarmingly clear that Bathsheba's dark intention is to possess mothers in order to kill their children.
With no time to lose, Ed and Lorraine seek out Father Gordan to facilitate an exorcism while the Perron family seeks refuge in a nearby hotel. Their brief respite is cut short when Carolyn drives back to the house with two of her daughters. Ed and Lorraine quickly arrive to find Roger and the police officer struggling to control Carolyn, who is in a trance, desperately trying to harm one of her daughters. Ed insists upon calling for the priest, only to be reminded that he is too distant to arrive in time, compelling Ed to conduct the exorcism himself.
As the others hold the constrained Carolyn down during the vital ritual, a moment of calm suggests that they may have succeeded. But this peace swiftly shatters as her chair flips and Carolyn levitates upside down. Ed boldly commands the demon to release her, and after a life-threatening standoff, Carolyn falls helplessly to the ground. In a frantic moment, she chokes out, "She's already gone."
Meanwhile, Drew discovers April hiding beneath the kitchen's floorboards, inadvertently triggering Carolyn's possession once more as she races upstairs. The entity forces Carolyn to pursue April, intent on completing the horrific sacrifice. Ed, Lorraine, and Roger urgently follow, arriving just in time to confront the possessed Carolyn. In a desperate attempt, Lorraine reaches down, grasping Carolyn's head, urging her to remember the profound value of her family and the irreversible consequences of her actions.
Slightly touched by Lorraine's plea, Carolyn's demeanor changes; her face softens, and she eventually places April down, the grip of evil seemingly loosening. The scene then shifts to a now bright and hopeful morning, as Carolyn emerges into the sunlight, her bruises visibly fading, and she is joyfully united with her family.
With the demon finally exorcised from the Perron home, Ed and Lorraine return to their own residence. As Ed steps into his room filled with possessed objects and artifacts, he places the ominous music box from the farmhouse onto a shelf. Lorraine joins him, and they exit together, leaving the music box momentarily silent. However, as the camera lingers, the music box ominously springs to life, filling the air with its haunting melody. The camera gradually zooms in on its reflective surface, and as the eerie tune concludes, the screen fades to black, ushering in the credits.
