In the seemingly tranquil town of Amityville, New York, the shadows of the horrific DeFeo family massacre from 1974 still linger. A new chapter of terror unfolds in the same parish church where Father Ronald DeFeo Jr. tragically took his own life. The reverend's remains now lie in solemn silence, while the confession booth, the site of his demise, has been moved to the dimly lit basement of the clergy house.
Fast forward twelve years, and Dr. Marvin, a prominent psychologist, alongside his wife Debbie, inadvertently revisits this dark past when they choose to make the clergy house their new home. Initially thrilled by their purchase, Debbie soon becomes haunted by an unsettling feeling that creeps through every corner of the property. Her anxiety is fueled by the musty basement housing the now-forgotten confession booth. Despite Marvin's attempts to calm her fears, Debbie’s nightmares escalate, often centering around that very basement. Dr. Marvin, the rational thinker, encourages her to document these dreams, hoping to unlock their psychological mysteries.
As they settle into their new life, they invite friends Frank, Bill, and Abigail over for renovations. During this time, they encounter the mysterious Mrs. Moriarty, a former church secretary whose enigmatic presence adds to the growing tension in the home. Her cryptic remarks add to the suffocating atmosphere, leading to increasingly inexplicable events. Unexplainable noises, shifting objects, and faint whispers echoing from the walls create a sense of dread. While some members of the household believe they are facing a malevolent presence, Dr. Marvin remains skeptical, attributing the occurrences to shared hysteria.
Hoping to escape the chilling atmosphere, the group goes out for dinner, leaving Frank behind, who is plagued by a severe migraine. Yet, the true horror begins when Debbie encounters Mrs. Moriarty in the bathroom, where her words take on an ominous tone, alluding to the haunted past of the priest who once lived there. The next day, disaster strikes as Mrs. Moriarty is found dead, her fall down the basement stairs captured on film by Bill’s abandoned camcorder. As the police investigate her death, they discover a shocking connection to the priest's past—a local teenager identified as the murderer, whose life was tragically cut short.
The chain of horror deepens when Debbie starts experiencing visions of a man hanging from a tree outside their home. The darkness surrounding the house seems to thicken, unraveling the very threads of reality. Abigail, overcome by a sense of panic, decides to leave. Meanwhile, Marvin, increasingly anxious, dives into the journals Debbie kept, revealing that her nightmares are laden with dark incantations meant for exorcism. In a horrifying revelation, Debbie dreams the truth about the priest’s demise: his own illegitimate son, born from a forbidden affair, shot him in a brutal act of revenge. Disturbed, Debbie searches for Marvin, only to discover his lifeless body in the shadowy depths of the basement confession booth, where she is confronted by Frank, now possessed by the vengeful spirit of the priest's son.
As investigators piece together Mrs. Moriarty's murder, they find evidence pointing to Frank through a grainy video that captures his familiar footwear. In a terrifying confrontation, Frank pursues Debbie through the house, culminating in a vicious attack using a processional cross. In a desperate move, Debbie manages to shoot him with a nail gun, but the horror doesn't end there. Abigail returns, only to find Frank has returned from the dead and attacks her violently. In a final act of survival, Debbie stabs Frank with the processional cross, ending his reign of terror.
Eventually, as the haunting echoes fade, Debbie and Abigail are led from the house by police officers. Just as they think they have escaped, a detective shows Debbie a photograph of an infant boy—the priest's illegitimate son—recovered from the crime scene. With a chilling realization, Debbie responds that this child belongs not to her, but to the cursed house itself.
