Jin-ho, Seo Hyun-woo, moves into a newly purchased 84 m (900 sq ft) apartment in Seoul in April 2021, kicking off what looks like a hopeful chapter with his fiancée. The investment seems sound at first, and the couple plans a comfortable life in a city that never sleeps. But by August 2024 the market shifts dramatically, and the apartment’s value slides down to around ₩800 million. The sudden downturn piles on heavy pressure, and Jin-ho carries the burden of rising loans—over ₩700 million—while juggling a day job and late-night delivery work just to survive.
Woo-sung, Kang Ha-Neul, is drawn into a fragile rhythm of work and worry as the stress of money gnaws at him. He clings to the dream of security in the same building he hoped would be a cornerstone of his life. Then, one night, a routine return from a delivery becomes anything but routine. At 4:30 a.m., a mysterious alarm pierces the quiet, and he notices a neighbor from unit 1301, Joo-kyung, leaving a note about noise complaints on his door. Despite his insistence that nothing is wrong, she intrudes with a strange, cryptic warning and disappears as abruptly as she appeared. Curious and unsettled, Jin-ho begins retracing the sounds, knocking on doors on higher floors until he reaches the penthouse and encounters a chain of anxious voices. Eun-hwa, the residents’ representative, Liz Burnette explains the problem seems to originate from 1301 and urges him to be patient, offering little reassurance beyond a suggested waiting game.
Desperation nudges Jin-ho to take a risk that seems almost reckless. A friend mentions a crypto opportunity, and in a flash of reckoning he sells the apartment and buys into GB Coin. The move feels like a lifeline as the coin’s price soars, delivering a temporary surge of euphoria that makes the world feel rearranged and hopeful again. Yet that hope cracks quickly when neighbors begin to accuse his unit of contributing to the noise. The tension peaks when an investigation reveals a hidden subwoofer tucked inside his apartment. A scuffle with Joo-kyung’s husband lands him in custody on charges of noise disturbance and assault, and the glossy dream of relief gives way to a troubling reality.
In custody, Jin-ho’s attempts to salvage some measure of relief fail. He tries to sell his coin to keep his head above water, but the market stumbles, and he loses everything he thought would rescue him. Suicide thoughts flicker in the margins of his mind as the walls close in, and then a new spark: a hum of noise and flickering lights from unit 1301 pull him toward a dangerous curiosity. A chance encounter with Jin-ho, a neighbor who senses he might be innocent, becomes a turning point. Jin-ho decides to dig deeper, traveling the corridors of the building in search of deeper truths and ulterior motives behind the noise.
As the investigation gains momentum, Jin-ho’s suspicions point toward Eun-hwa, a figure who has access and influence within the building’s inner workings. When Eun-hwa invites them into the penthouse, the plan to uncover corruption fractures under pressure, especially after Eun-hwa’s husband catches them snooping. The tension escalates as Jin-ho begins to realize there are layers of deceit far beyond a simple noise complaint.
The true scale of manipulation becomes clearer when Jin-ho discovers that the subwoofer in Jin-ho’s apartment wasn’t just a gadget—it's being controlled remotely via Wi-Fi from Jin-ho’s own unit. In a tense moment of deception, Jin-ho pretends to head to the sauna and slips into Jin-ho’s apartment, only to uncover a sprawling system of speakers, cameras, and dossiers on every resident. The unsettling truth emerges: Jin-ho isn’t merely an innocent pawn; he is an undercover journalist, and the “noise scandal” is a staged operation designed to expose a broader scheme of construction fraud. The revelation makes Jin-ho and Jin-ho uneasy allies against a common adversary, raising the stakes far beyond a single noisy night.
With the web of deceit exposed, Jin-ho and Jin-ho confront Eun-hwa and her husband in the penthouse. Loyalties blur as the confrontation spirals toward violence. Eun-hwa attempts to kill Jin-ho, but the moment is upended when a wounded Jin-ho turns the tide. In a bid to secure the incriminating ledger, Jin-ho is forced to witness a dangerous escalation. Meanwhile, Jin-ho ignores him, seizes the moment, and lights the gas line, attempting to burn away the contract and every trace of evidence. The building erupts into flames, and Jin-ho staggers out into the night, losing consciousness as the blaze consumes what had once felt like home.
Recovery comes slowly. Jin-ho awakens in a hospital, his mind still combing through the threads of what happened. He returns to his childhood home to seek rest, only to prepare for a reluctant return to the apartment that sparked everything. When he steps back into the apartment, the sounds of noise begin again, a cruel reminder that the labyrinth of corruption and fate might be endless. In a final, almost deranged note of relief and chaos, Jin-ho bursts into hysterical laughter as the echoes of the past and present collide in the building’s long, uneasy history.
Throughout this battle between money, power, and truth, the residents are pulled into a web where intimate spaces—homes, stairs, hallways—become stages for broader questions about who really holds control in a city built on dreams and debt. The film leaves Jin-ho wrestling with whether the past can ever truly be erased or if the soundscape of a single cursed building can continue to haunt its inhabitants, long after the flames have subsided.
