Single mother Sung-hee moves into a new apartment and installs a homecam to protect her sick daughter, Ji-woo. She also hires a babysitter. While closing a suicide case at her insurance job, Sung-hee hears an eerie, ritualistic chant in the recorded footage. Soon after, she begins to witness a mysterious woman and Ji-woo's strange behavior on the homecam. As she digs deeper into the case, an unseen force begins to close in on her. Su-rim, a shaman living downstairs, suggests performing an exorcism ritual.