A young family hire a nanny to look after their newborn daughter. After gaining the trust of the young parents, the nanny begins scaring their daughter and older son, Egor, at night. Egor tells it to his parents but they don’t believe him. One day Egor comes home to find that his little sister has disappeared along with the nanny. His parents are in a strange trance-like state and don’t remember ever having a daughter. Egor sets out with his friends to look for his sister. They are convinced that the nanny is actually an ancient Slavic demon that once went by the name Baba Yaga.