The film follows Ji-won (Ha Ji-won), an investigative journalist who becomes the target of threatening phone calls after exposing a pedophilia scandal. To escape the harassment, she changes her phone number and moves into a secluded house owned by her friend Ho-jeong (Kim Yoo-mi). However, the disturbing calls persist, and Ho-jeong's daughter, Young-ju (Eun Seo-woo), begins to exhibit strange behavior after answering one of these calls. As Ji-won delves deeper into the mystery, she uncovers a tragic connection to a previous owner of the phone number, leading to a chilling revelation.
