In which vampire Tzuyu decides to crash a Halloween costume party out of pure curiosity. She even goes as far as to dress the part to ensure that she successfully infiltrates the human-hosted event. There, she meets Nayeon, who refuses to wear a costume of any kind and subsequently causes the powerful and feared vampire to feel absolutely ridiculous.  

  Paranormal investigator Kim Seolhyun is informed that her former lover Shin Hyejeong will soon ascend to a higher position in the Order of Exorcists. A bitter Seolhyun decides to become the devil's advocate for her ex-girlfriend by cooperating with her on a case and gathering the necessary evidence to reveal Hyejeong's potentially career-ruining secret: her embarrassingly strong fear of supernatural entities (despite her exorcising them for a living).