On a remote island, an amnesiac drifter named Isaac is hired by his acquaintance and landlord Moe Barrett to look after his niece Olga, who can slip into catatonia with little warning. This mysterious condition puts Olga at risk as she resides alone in a secluded, storm-battered house. To manage the arrangement, Isaac is forced to wear a heavy harness that confines him to certain parts of the home, a stark reminder of the house’s dark control over everyone who enters it.
Moe explains a chilling family history: Olga's mother went missing after locking her husband in the basement, while Olga's father descended into a crippling claustrophobia and ultimately took his own life. The house grows even more unsettling as Isaac discovers that when Olga is lucid, she roams with a crossbow and an eerie toy rabbit—its human-like glass eyes fixed on him and an attached drum that seems to tremble with hidden secrets.
As strange, almost supernatural phenomena begin to unfold, Isaac uncovers Olga's mother's corpse concealed behind a wall in the basement. The rabbit doll acts as a dowsing rod, its drum beating louder whenever something hidden within the house draws near. Olga warns Isaac that Moe will not allow him to leave, and she reveals a grim truth: Moe and Olga's father were the ones who killed her mother. Moe also once planned to kill his brother but restrained himself. He had recruited Isaac to lure Olga's father into the basement and lock him there, a plan Moe confirms when Olga has him call Moe.
In a desperate bid to escape, Isaac frees himself from the harness by taking the key from Olga's mother's corpse. Olga cuts the power and attempts to kill Isaac, but the act leaves her briefly catatonic. Seizing the moment, Isaac traps Olga back in the harness, though she shoots his leg with the crossbow. Memory returns for Isaac, revealing that he was not responsible for Olga's father's death; he had second thoughts and had tried to warn him via a note Moe discovered.
Moe brutalizes the situation further by pushing Isaac off a balcony, though Isaac survives with amnesia. Desperate to flee, Isaac crawls through a narrow space and is stalked by the ghostly presence of Olga's mother. The crawl space leads back to the basement wall where Olga's mother lies, and Isaac notices the corpse's head has shifted as he stares through a small opening.
Moe arrives and glimpses Isaac through the hole in the basement wall. Olga then shoots Moe with the crossbow, climbs back upstairs, and locks the basement door behind them. Through the intercom, Isaac proclaims that he has already escaped the house by another crawl space, leaving Moe to confront the unsettling truth of his actions.
Outside, Isaac frees a chained dog and makes his way to the doorway, where he finds Olga standing on the threshold, still wearing the harness and clutching the crossbow, their eyes meeting from a cautious distance. The final tension rests in the narrow divide between escape and imprisonment, as the two characters confront an uncertain future beyond the walls that once contained them.
