In 1975, the scene is set in Amityville, Long Island, New York, where paranormal investigators Ed and Lorraine Warren (Patrick Wilson and Vera Farmiga) sit down with the troubled Lutz family, who claim their home is haunted. This residence is infamous due to the horrific murder that took place there a year ago, where Ronald DeFeo, Jr. brutally killed his family with a shotgun. During a séance, Lorraine experiences a chilling vision; she sees herself in Ronald's place during the tragic night, committing heinous acts against his family. Amid this nightmarish imagery, she is confronted by a demonic entity in the shape of a nun, culminating in the sight of a man perishing. Ed quickly pulls Lorraine from the horrifying vision, providing her some much-needed comfort.
The narrative then shifts three years later to Enfield, England, where we meet Janet Hodgson (played by Madison Wolfe), who is outside her school with her friend Camilla (Emily Tasker). As they engage in playful rebellion by smoking cigarettes, a teacher catches them, leading to a scolding and the confiscation of their smokes. Janet's life at home is filled with turmoil; she lives with her older sister Margaret (Lauren Esposito), her younger brothers Johnny (Patrick McAuley) and Billy (Benjamin Haigh), and their struggling mother Peggy (Frances O'Connor). Their recent financial hardships are compounded by the emotional fallout from their father abandoning them for a neighbor.
At night, a disturbing presence begins to plague Janet as she sleeps. Initially dismissed, the situation escalates when she experiences an eerie voice that claims, > "This is my house!" Convinced that something sinister is afoot, Margaret and the others are soon forced to acknowledge the harrowing reality when physical disturbances shake their home.
Meanwhile, back in America, Ed and Lorraine are invited onto a talk show to discuss the Amityville case, but their claims are met with skepticism, leading to a heated argument. Lorraine's emotional state is frail, and she feels the weight of the paranormal world pressing down on her.
As the story unfolds, Janet ties herself to her bed, only to wake on the living room floor, confused. Her brother Billy encounters a haunted firetruck while experiencing nightmarish visions himself. Their home quickly transforms into a nightmarish landscape where paranormal phenomena raises the stakes for the Hodgson family. With things spiraling out of control, multiple encounters with ghastly apparitions, voice changes, and chaotic activity, the children and their beleaguered mother reach out for urgent help.
In a desperate twist of fate, Ed and Lorraine travel to Enfield to aid the Hodgson family, following unsettling reports and the disturbing voices emanating from their daughter Janet. What begins as a pursuit to aid becomes a race against time as Lorraine is repeatedly haunted by visions of Ed's potential death.
Through heart-stopping encounters, ghostly presences, and ominous warnings, the Warrens uncover a deeper connection to the names and spirits controlling the chaos, particularly that of a malevolent demon named Valak, coming to grips with a destiny intertwined with their own lives.
In a climactic showdown, Ed manages to save Janet in a near-fatal event as Lorraine confronts the demon. With great effort, they restore peace to the Hodgson family and manage to lock the dark entity away while noting that the case of the Enfield haunting becomes one etched into history.
As dawn breaks, gratitude fills the air when Peggy and her family express heartfelt thanks to the Warrens. With the haunting at an end, Ed places the eerie Crooked Man turntable in his museum, only to be met with the melodic strains of "Can't Help Falling in Love With You" wafting from upstairs, where he and Lorraine share a poignant dance, a sweet moment amidst the chaos they’ve faced.
