Noise (2024)

Joo-hee lives in apartment 604 and has become disturbed by strange noises coming from upstairs. She installs soundproofing material on her ceiling and records the noise levels with a sound meter. After seeing the high decibel reading, she angrily declares that she will gather evidence. When the doorbell rings, she receives only the eerie laughter of a woman through the intercom. As the noises from upstairs continue, Joo-hee takes her camcorder and leaves the apartment.

Four days later, Joo-hee's older sister Joo-young learns from detective Kim Hong-gyu that her sister has gone missing. Returning to their apartment, Joo-young finds a threatening note apparently left by Geun-bae, the resident of apartment 504. Inside, she discovers that Joo-hee had covered the living room with soundproofing materials. She also finds a strange mold-like substance in Joo-hee's room. Geun-bae arrives and complains about the noise, claiming that he can no longer tolerate it. Joo-young later tells the detective that she suspects him of abducting Joo-hee, but he says there is insufficient evidence.

Joo-young discovers a recording that Joo-hee had prepared as a birthday gift for her, along with a hearing aid. She unlocks Joo-hee's phone and identifies the number from her sister's final call. At Joo-hee's workplace, she meets Ki-hoon, who had been close to her sister. Meanwhile, Geun-bae continues to harass Joo-young and eventually becomes convinced that the noises are coming from apartment 704 rather than 604. When he goes upstairs to investigate, the ghost of the woman who lived in 704 appears and pursues him. While fleeing, Geun-bae falls from the seventh floor and dies.

After Geun-bae's death, Joo-young discovers that the threatening note outside her apartment has mysteriously become blank. When she removes it, she finds her own name, "Seo Joo-young," scratched into the paper. Joo-young and Ki-hoon investigate the building's history and learn that a former resident of 604 was allegedly responsible for killing the former head of the residents' association who lived in 704. They enter an unused basement storage area, where they become separated. Ki-hoon finds the corpse of the former 604 resident and, after hearing a horrific sound, begins behaving strangely. Meanwhile, Joo-young discovers a sketchbook depicting the car accident that killed their parents. The drawings reveal that Joo-young had distracted their father while he was driving, causing the accident. She later encounters the disturbed Ki-hoon, who attacks her, but she manages to escape.

Joo-young is eventually found by the head of the residents' association, who tells her that the police were called after she claimed someone was in the basement. She learns that the daughter of the resident of 804 had died years earlier after being struck by a delivery truck. The head's son, Yeon-woo, communicates with Joo-young through sign language and tells her that she has heard something she was not supposed to hear. Joo-young then discovers that Ki-hoon has died and returns to the basement. There, she finds Joo-hee's camcorder and watches its final recording. The footage shows Joo-hee entering apartment 804 after realizing that the noises were coming from there. She discovers speakers connecting the ceiling and floor and witnesses the woman from 804 speaking as though to her deceased daughter. The woman admits to killing the former head of the residents' association in 704 before attacking Joo-hee and ending the recording.

Joo-young eventually finds Joo-hee in the basement, but the woman from 804 appears and pursues them. Joo-young hides her sister and attempts to lure the woman away. During their confrontation, the woman claims that she never intended to kill the residents of 704 or Joo-hee, but that they had insulted her daughter. Just as she is about to kill Joo-young, the ghost of the woman from 704 appears and attacks her. The woman begs Joo-young for help, but Joo-young shuts the door and escapes. She then finds Joo-hee and embraces her, telling her not to listen to the sounds around them.

Some time later, a new resident moves into apartment 704 and visits Joo-young. When asked whether she lives alone, Joo-young says that she lives with her younger sister. Joo-hee appears behind her, still wearing the same clothes and appearing as she did when she disappeared, but the new resident cannot see her. It is revealed that Joo-hee had actually died during her encounter with the woman from 804 and that Joo-young, unable to accept her sister's death, has been hallucinating her presence.