A family is troubled by disturbing events that leave everyone wondering what is real and what is an illusion. Two sisters, Su-mi (Im Soo Jung) and Su-yeon (Moon Geun Young), struggle to deal with their step-mother Eun-joo (Yeom Jeong-ah) after their real mother’s recent death while their father Moo-hyeon (Kim Kap-su) is distant and in mourning. They resent her, and begin to believe that she is malicious. Scratches appear on Su-yeon’s arms, and Eun-joo’s behavior becomes more erratic and dangerous every day. Su-mi tries to defend her sister and her father, but Eun-joo always gets the better of her. When Eun-joo locks Su-yeon in a wardrobe, Su-mi decides she’s had enough. What she learns next turns everything she thought she knew about her family upside-down.