Kyungchul is. He has committed infernal serial murders from diabolic ways this you may not imagine and his victims range to kids. He has been chased by Law enforcement for quite a long time, but were struggling to grab him. Joo-yeon becomes his prey one day and can be found dead in a state. A best secret agent, her, decides to track down the murderer himself. He promises himself that he will do everything in his power to take vengeance against the killer, even if this means that he has to turn into a creature himself to get this killer.