The beginnings of the strange investigation stem from one former detective Kim Yoon-seok's Eom Joong-ho now turned a pimp. His story begins with him working on the strange disappearances of his women stemming unfortunately from them being murdered by the killer. Kim portrays the part as a man with little care for the world, or anything around him. He brings just kind of a general discontentment in hearing about the loss of the girl that Kim depicts as much due to his own state as a man than any real concern for the women. Of course Eom believes they have simply been stolen from him by a rival pimp rather than anything too problematic. Kim's work just carries this general ambivalence fitting to such a man who is working in the profession that only seems to carry this underlying shame, but yet he just keeps at it. Unfortunately the women he is sending in are actually being murdered by the serial killer Je Yeong-min (Ha Jung-woo), who Eom literally accidentally crashes into. This leads towards Eom's sort of resuming his older profession when he sees blood on the man's shirt and naturally takes physical effort to apprehend the man. Kim handles this scene in particular by just capturing the real gut reaction of the man emphasizing the moment of confusion before realizing this sort of random anger as he beats the man down before both of them are arrested.
Both are arrested initially where the mentally ill Je confesses his crimes, meanwhile Eom is initially just kept to be used as a scapegoat for the police to explain the killer's injuries to avoid any accusations of police brutality. Kim's performance properly embodies this strange state of the man just stewing in frustration as he is mocked for being a pimp while trying to explain the far worse criminal who was brought in with him. One thing leads to another though and Eom becomes an independent investigator as he tries to uncover what happened to the women. These are Kim's most effective scenes as he depicts Eom's discovery of the horrors of the killer, and gradually portrays this awakening in Eom. This is not only in terms of a loss of that ambivalence but also a more striking sorrow as he begins to find clues that allude to a real darkness. Kim's rather moving even in finding essentially the stronger morality of the man reveals itself, and the growing empathy for the women he had so carelessly put into harms way originally. Although the film is a bit messy in its plot developments Kim remains a driving force of the film by capturing this emotional state of the man that he intensifies the more he understands of the murderer's horrors. This is along with taking in the daughter of the last prostitute he accidentally sent to the man. This relationship really is not developed all that much beyond really Kim's performance. Kim though does well in bringing that terrible sadness in his eyes when he watches over the girl showing it as the sense of loss attached to the mother he originally spent little time thinking about originally. Kim becomes the emotional anchor effectively and keeps this state as he shows the man slowly fall apart the more horrifying the situation becomes. Kim does this well though by showing it coming from empathy through his eyes that accentuate care which stands in stark contrast to the hollow selfish man we saw in the opening. Now this idea isn't as powerful as it could be through the film's muddled storytelling and the fact that Eom's original downfall probably should have been better established. Kim makes the best out of the material he does have to give a moderately compelling turn. The ideas behind the role and character though are not fully developed though by the film's script leaving Kim to have to carry more weight than he should have had to. It stands as a good performance but one limited by the underwhelming material behind it.