Architect Sang Won, who lost his wife in a sudden accident, and his daughter, Yi Na, move to a new house to restore their estranged relationship. Sang Won tries to get closer to Yi Na, but their relationship hardly recovers. Then one day, Yi Na becomes cheerful again saying that she got a new friend. However, strange noises start coming from Yi Na's closet, and she starts acting abnormally. And not long after that, even Sang Won begins to have strange dreams, and his daughter then suddenly disappears. While looking for Yi Na, Sang Won gets a call from a mysterious man named Kyung Hoon, who tells him that Yi Na is not the first one to disappear and that he has been looking for 32 other missing children for the last 10 years. Sang Won and Kyung Hoon then join forces to find Yi Na and solve the mystery of the missing children.