In 1928 England, David Ash, a professor of parapsychology, has spent much of his life trying to debunk the existence of ghosts, haunted by the death of his twin sister Juliet Ash when they were children. After Juliet’s death, he and his mother moved to America, seeking distance from the past that still clung to him.
During a laboratory séance, he exposes the medium’s tricks, only to be startled when a voice that sounds like Juliet calls his name. The incident blurs the line between skepticism and something troublingly real, drawing him back toward the very mysteries he rejects.
A request comes from a woman who identifies herself as Miss Webb, pleading for help with spectral disturbances at a house named Edbrook. At Oxford, [David Ash] is told the caller is actually their Nanny Tess, and that she has inspired the Mariell siblings—Robert Mariell and Simon Mariell—to worry about her sanity. The siblings insist Tess is slipping, doubting her ghosts, and urge David to come to the palatial Edbrook House to test the phenomena firsthand. He travels to Sussex, where he is picked up by Christina Mariell, who explains the complicated web behind the plea: Tess is their nanny, and she wrote to him at their urging to verify what they fear.
At Edbrook, David begins a careful forensic examination of the house, seeking any sign of supernatural activity. The atmosphere tightens as Christina’s flirtatious charm lingers around him, while Robert Mariell resists the growing bond and guards his siblings’ secrets. As the investigation deepens, Tess’s alarming visions become intertwined with memories of the Mariell family. Christina discloses a painful truth about her past—her mother drowned in the lake and Tess was the one who discovered the body—suggesting that Tess’s trauma might be feeding the haunting of the house.
David contemplates leaving Edbrook and asks Christina to accompany him. She refuses, yet their kiss and later a night of passion complicate the emotional terrain. When dawn breaks, the house is shrouded in wind and shadow, its rooms draped in black and strewn with fallen leaves. Following the ghostly guidance of Juliet, David travels to a graveyard where a tombstone reveals a grim secret: [Robert Mariell], [Christina Mariell], and [Simon Mariell] all perished in a fire at Edbrook in 1923.
Seeking answers, David seeks out Dr. Doyle, the family doctor, only to be told, through Juliet’s spectral warning, that Doyle appears to be dead. Undeterred, he rides with Christina, but on the road the vision of Juliet reappears, causing him to swerve and crash the car. Christina is killed, and David staggers back to the house to confront Tess. Tess confirms that the Mariell siblings are dead and that their ghosts will stop at nothing to keep him from leaving. The trio of siblings materializes and compels Tess to confess to their murder; Tess herself is slain as the ghosts tighten their hold.
The supernatural horror crescendos as the mansion is set ablaze. David fights his way across the burning corridors, pursued by the living dead of the Mariell siblings and blocked by Doyle. In a final blaze of flames, Juliet returns, walking through fire to reach him, take his hand, and lead him away from the ruin. She frees him from guilt over her death and steps toward the afterlife, leaving David to face the quiet aftermath of the night’s terror.
Back on solid ground, David is met at the station by his assistant, Kate, a calming return to normalcy. Yet the fog swallows the platform, and out of the shadows, Christina quietly follows the departing couple, hinting that the danger at Edbrook may not be fully behind them.
