Ju-young is a young woman with a hearing impediment who decides to investigate her sister's inexplicable disappearance, last seen in her apartment. Feeling more and more cornered, Ju-young begins to hear strange sounds and sense an evil presence in the apartment.

On an ordinary day, Yoon-jin(26) finds Ji-hoon(14) crouching down on a stair in the hallway in front of her house.