Soo-hyuk, an elementary school teacher in a rural village, has a secret. Every night, his wife Yi-young turns into another person. One day, the father of one of his students comes to know of their secret. Soo-hyuk begs him not to tell anyone, but the father informs the village that a spirit possesses Yi-young’s body, and they decide that every night she is to be locked in. cage.

Unable to bear the thought of leaving his wife alone, Soo-hyuk too goes into the cage with her, but tragedy strikes, and the formerly quiet village is turned upside down. When detective Hyung-gu arrives in the town to investigate, he soon becomes more embroiled in the case than he ever thought possible.