Wives Hyun-su and Soo-jin face an unexpected challenge when a man starts walking in their sleep and saying horrible things. Every night he turns into a different person and in the morning he has no memory of the night's deeds. Soo-jin is paranoid that Hyun-su might accidentally hurt himself, her or their unborn child. The family doctor diagnoses an extreme REM sleep disorder, and a meeting with a shaman sows the idea that the man's transformation symptoms are related to the paranormal.