Emma (Elisabeth Moss Elizabeth Moss) moves into a new house with her parents, but the eerie atmosphere here makes the family feel uncomfortable. One day, Emma walked into the attic and saw a girl who looked like her, and the other person obviously had a grudge against her. Suspicious Emma launches an investigation with the help of Detective John (Jason Lewis Jason Lewis) and discovers that her parents may practice dark magic secretly, and she does have a twin sister. On the twelfth day of her birth, Emma's sister Beth (Lynne Marie Stetson) is killed. Now, the resentful Beth returns to earth, vowing to take revenge, and Emma's behavior is getting out of control.