Joong-ho is a dishonest ex-detective turned pimp who is in financial trouble because two of his prostitutes have gone missing. One night, he commands Mi-jin to service a customer, despite her protests over her sickness. Joong-ho then realizes this customer was the last to see his missing girls. Believing that this customer is trafficking his women, Joong-ho nevertheless sends Mi-jin in so that she can forward the customer’s address to him. Joong-ho contacts his old police task force for help, but they cannot assist because the mayor of Seoul, whom they were guarding, has been attacked with feces; this results in the police suffering a media firestorm.The Chaser 2008 .
The customer, Yeong-min, takes Mi-jin back to a house but Mi-jin fails to contact Joong-ho due to the bathroom having no cell service. Yeong-min binds Mi-jin, but her struggles prevent her murder with a chisel, so Yeong-min hits her with a hammer, knocking her out. Just then, an elderly couple from the local church arrive, inquiring about the real house owner, Mr. Park; they recognize his dog. Yeong-min then invites the elderly couple in and murders them.
Joong-ho, only aware of the customer’s district, conducts a search. Yeong-min tries to ditch the couple’s car, but collides with Joong-ho’s car. Joong-ho’s suspicions are aroused as Yeong-min has blood on his shirt and refuses to give his phone number. Joong-ho calls the customer’s number and Yeong-min’s phone rings. Yeong-min flees but is caught and beaten by Joong-ho. Both men are arrested by a local cop. At the station, Yeong-min casually admits that he committed nine murders. Competing police divisions argue over who will investigate the high-profile unsolved murders in the area.Despite the confession, the police have no physical evidence so they cannot detain Yeong-min for long. Yeong-min reveals Mi-jin is alive, but the police doubt it. Joong-ho goes to Mi-jin’s apartment to collect DNA samples, and from there he takes Mi-jin’s daughter Eun-ji with him while he follows up a lead in Yeong-min’s hometown. Joong-ho learns that Yeong-min was jailed for three years for lobotomizing his own nephew. Another prostitute informs Joong-ho that Yeong-min is impotent.