When Seung Do , a heart specialist, and his wife find their daughter So Mi, showing strange symptoms by the day, they decide to attempt an exorcism ritual. Upon arrival, Priest Ban is sure there is the devil inside her, and the ritual seems to drive it out successfully, but ends in So-mi's sudden death. As her funeral begins, Seung Do, who notices some strange signs in So-mi's body, confronts his conviction that she may not be dead yet, and her heart is still beating. No one believes him, especially Priest Ban, who strongly opposes him saying that it is by the menacing spirit inside her. During three days of So-mi's funeral, they must each uncover the terrifying truth about the mystery, and prove who is right, to save her.