The film tells the story of a genius prosecutor named Huang Shimu (Cho Seung-woo) who lost his emotional nerves after a brain surgery as a child. He has been fighting alone in the corrupt Procuratorate for 8 years, until one day a strange corpse led him into a horrific serial murder case. Bae Doona plays the female police officer Han Yeo-jin, who has a strong sense of righteousness. After being strictly selected to join the core serious crime team, she begins to assist Huang Shimu in investigating the case.