Highly decorated homicide detective Choi Chang-sik has an enviable record and the respect of his peers. Days before a promotion, he dozes off on his way home after a celebratory drink with his colleagues. He wakes up to find that his taxi driver has taken him to a remote mountain trail and has pulled a knife on him. The two struggle, and Choi manages to kill the taxi driver in self-defense. Afraid that the incident would negatively impact his career, he covers up the crime scene and flees. The next day, the taxi driver's dead body has been strung up on a crane in front of the police station, and Choi is assigned to the case amidst widespread media attention. Choi's ordeal begins as he tries to misdirect the investigation and remove evidence, to the growing suspicion of rookie detective Cha Dong-jae. Then a man claiming to be the killer turns himself in and threatens to reveal the truth unless Choi reopens an old case.