Jane Emelin Juliette Lewis inherits a rent-controlled brownstone from her late aunt and, intent on proving she can live alone, chooses to move in despite the protests of her boyfriend Greg Harrison William Hurt. Right from the start, the building starts to feel crowded with small, unsettling signals. Her first-floor neighbor, Martha Stewart Shelley Duvall, offers a breezy tour of the occupants and naming the residents, including the enigmatic 4th-floor inhabitant, an elderly, reclusive woman we never actually meet. Yet the real strangers soon reveal themselves in quieter, more invasive ways: a note on the door warning about the noise of moving, then a second note that pushes Jane to call a locksmith who lives in the building across the way—a timer-tick of unease that never quite released its pressure.
The locksmith Tobin Bell is a strange, almost spectral figure who seems to watch Jane as she steadies her new home. Amid the creeping tension, Jane befriends Albert Collins, a gentle, older man who shares a long history with Greg from high school. Their bond gives Jane some warmth, but it’s strained by Greg’s insistence that she should move in with him, and by an argument that culminates in her downstairs neighbor smashing tiles on her kitchen floor. When she calls the police in anger, the response only fuels a cycle of louder confrontations, louder apologies, and a mounting paranoia that she’s never quite hearing things the same way again.
Tripping on a grease-smeared stair, Jane tumbles and then tries to mend fences with a heartfelt note asking for a truce. But the apartment’s plumbing of misfortune only deepens: her tub and entire place get infested with maggots and mice, a hideous domestic nightmare that forces her to call an exterminator drawn into something far more ominous than a simple infestation. The exterminator Robert Costanzo hints that the mice problem isn’t an accident and suggests a hole drilled into Jane’s floor—likely by a neighbor who wants to keep her in the dark and under control. A Korean grocer briefly underscores that the downstairs neighbor, Alice, had suddenly stopped ordering groceries, amplifying Jane’s fear that she’s being watched more than she can bear.
Desperate for any evidence, Jane decides to break into the 4th floor to document what’s really going on. There she discovers a nightmarish tableau: mice and rats confined in cages, a typewriter that seems to echo with messages, a ceiling swarming with Jane’s furniture arranged in an almost ritual map, and the word “Portcullis” scrawled on a wall like a warning. A threatening package arrives—a blasted collage of packing noodles from the trash bags outside Alice’s door, paired with a shocking discovery: photographs of her aunt’s dead body. Panic becomes planning as Jane wraps the evidence to take to the police, but the unknown neighbor strikes first, knocking her unconscious and stealing the evidence.
Back in the hospital, Greg tries to soothe her fears and persuade her to leave the apartment, arguing that no one believes her, that the danger isn’t real. She resists, but the world refuses to settle. She returns to confront the door of the downstairs neighbor, banging and demanding answers, only to be steadied by Collins, who takes her back to his place. It’s there, under the quiet, dim light of a ceiling with recurring patterns, that the word “Portcullis” appears again, and the terrifying truth emerges: Collins is the one she has been running from—the terrifying force in the 4th-floor world she thought she knew.
The confrontation explodes into a brutal struggle. Collins drags Jane up to the 4th floor, into a room choked with flies and a body slathered in maggots—presumably Alice. Her attempts to escape are thwarted as the attacker breaks through, the phone line dies, and a door knob is tethered to a stair railing. The locksmith appears in the chaos, providing a human line of defense, but Collins proves formidable. In a desperate fight, Jane drives a crowbar into Collins and, in a final act of rescue, Greg arrives to attempt to wrestle the knife away. Collins refuses, raises the blade, and is toppled over the railing, his scream trailing down the five flights of stairs to his death.
Months later, Jane has begun to put the nightmare behind her, but the wound remains. She chats with a coworker, Cheryl Sabrina Grdevich over the phone in Greg’s apartment, and the locksmith who watched from his window—painting and sketching what he sees—offers her one last image of what his surveillance has captured. The final scene lingers on his paintings, ending with a haunting drawing that shows Greg and Collins at a table beside the same typewriter used to type threatening messages to Jane. The film closes on this eerie, unsettling tableau, leaving open questions about who is watching whom, and who ultimately holds the power in a building that no longer feels like a home.
