Soo Hyuk is a teacher at a village primary school. He has a secret: every night, his wife Yi Young turns into another person. One day, the father of one of his students learns of their secret and tells the villagers that Yi Young's body is occupied by an evil spirit every night. The villagers agree that Yi Young is very dangerous, and they ask Yi Young to enter a locked cage every night. As a result, the couple soon died in a fire of unknown cause. A detective was sent to investigate, and he interrogated the villagers one by one, and the atmosphere in the village gradually became weird. One night, the villagers invited the detective to the town hall for a drink. After drinking, the detective lost consciousness. The next day, the detective woke up in the same cage as before, but everyone called him "Teacher". He realized that he had turned into Soo Hyuk...