The film is based on a true story and revolves around two detectives, Park Doo-man (played by Kang-ho Song) and Ki-woo (played by Kim Jae-wook), who are tasked with solving a series of gruesome murders in a small town in South Korea in the 1980s. As the investigation unfolds, they are joined by a Seoul-based detective, Seo Tae-yoon (played by Shin Ha-kyun), who brings a fresh perspective to the case.