Ju-young, a young woman with a hearing impairment, embarks on a quest to uncover the mystery behind her sister's sudden and unexplained disappearance. Her sister was last seen in her own apartment, prompting Ju-young to delve deeper into the unsettling circumstances. As she investigates further, she starts experiencing eerie noises and sensing a malevolent presence lurking within the apartment walls. With each step, Ju-young feels increasingly trapped, intensifying the suspense and uncovering a chilling secret behind her sister's vanishing.