Theo Conroy, portrayed by Kevin Bacon, finds himself in a tangled web of nightmares as he navigates life after retiring from banking. He is married to the bright and ambitious Susanna, played by Amanda Seyfried, and together they share a young daughter named Ella, brought to life by Avery Tiiu Essex. One day, when Theo attempts to visit Susanna on set, he faces an unexpected roadblock—his access is denied. His discomfort escalates when he discovers Susanna is filming a provocative scene, unveiling an unsettling layer of their relationship coupled with a hint of public disdain towards him.
In an effort to escape the growing unease, the Conroy family decides to temporarily retreat to a vacation home in Wales before Susanna's work commitments pull her to London. While the house appears spacious and inviting, an eerie undercurrent quickly surfaces. As time feels oddly distorted and both Theo and Susanna struggle with unsettling dreams, Ella's innocent shadow puppets take a haunting turn when she perceives a shadowy figure lurking on her wall.
The following morning, Ella questions Susanna about the negative perceptions surrounding Theo, prompting a hesitant admission from Susanna about Theo’s past: his first wife tragically drowned in the bathtub, leading many to speculate he was involved, despite his acquittal following a sensational trial.
Armed with groceries, Theo ventures to town, where an inquisitive shopkeeper prompts unsettling questions about the home’s supposed owner, Stetler, and recommends measuring the house's angles—a puzzling suggestion that only deepens Theo's confusion. Upon returning, he learns that Susanna has revealed sensitive information to Ella, which incites tension between him and Susanna.
One evening, while Susanna enjoys a bath, Theo's curiosity leads him to snoop through her devices, resulting in a futile apology for their earlier conflict. As he roams the house, he stumbles upon a hidden staircase in the bookshelf and experiences a harrowing vision of Ella's lifeless body, frantically attempting to wake himself from the nightmare.
The next day, Theo witnesses Susanna and Ella outside, prompting an instinct to reach out to Susanna via text. However, he is stunned to find another identical phone displaying his messages. Concerned, he checks his journal, where a chilling warning appears: "You should leave. Go now." Confronting Susanna about the duplicate phone leads to an explosive argument, revealing her affair with another actor named Max. Crushed, Theo tells her to leave for the night.
Alone with Ella, their reality continues to warp—after measuring the kitchen, they uncover that it is larger inside than outside. Ella wanders off to fetch her coat but disappears, thrusting Theo into a panic. Their separate realities intensify as they each navigate their nightmares differently. In a desperate call for help, he learns from the shopkeeper that there are no taxis and that the house seems to claim souls.
As they prepare to leave, Theo and Ella find themselves drawing closer to the haunting figure that watches them from the window of the house. With no alternatives left, they resign to stay one more night. During this time, Theo dives back into the dream world where he encounters his prior self and recalls the moments of their first visit to the house, only to find Ella ensnared in a haunting grasp.
Meeting the enigmatic Stetler, who embodies Theo's own likeness, Theo is challenged to fulfill a dark obligation to reclaim his daughter. Ella's return brings a moment of joy, but as reality unfurls, Theo confesses his dark past concerning his first marriage—he didn't directly take her life, but his inaction led to her demise. Accepting his haunting association with the house, he is met with horror from Susanna.
Ultimately, the tragic conclusion traps Theo's soul within the very home he sought refuge in, echoing the ominous phrase that "some people don't leave the house; the place finds them." A chilling endnote, the house is then seen listed on a familiar booking site, a fate sealed for the next unsuspecting visitors.
