Architect Sang Won, who lost his wife in a traffic accident, and his daughter, Yi Na, move to a new house to restore their estranged relationship. But their relationship hardly recovers. One day, Sang Won hears a scream from Yi Na's room but she denies it. From that day, Yi Na becomes cheerful, saying that she got a new friend. Strange noises come from her closet & she starts acting abnormally. Not long after that, even Sang Won begins to have strange dreams, and his daughter then suddenly disappears from the house. After a months searching, people start getting suspicious of Sang Won. A mysterious man approaches Sang Won, under the prestense of fixing his internet connection. When the lie is caught, the man tells Sang Won that Yi Na is not the first child to disappear.