In 1990, detective Choi Hyeong-goo hunts down a serial killer who has killed 10 women since 1986, and whom he suspects is responsible for the kidnapping of another. He managed to hunt down the killer. After a fierce fight that leaves Choi nearly dead and permanently scarred, the killer escapes, but not before Choi shoots him in the shoulder. In 2005, 15-year after the last victim's murder, the expiration date for the
statute of limitations approaches, which will render prosecution impossible. Choi is an alcoholic, haunted by his failure to solve the case. He receives a call from Jung Hyun-sik, a family member of one of the victims. Choi rushes to his apartment, only to see Jung throw himself off a roof and crash through the windshield of a passing bus. Two years later, a man called Lee Doo-seok releases a book titled
I Am the Murderer, claiming responsibility for the 10 murders. His book contains detailed descriptions of the crimes, and he has a gunshot scar on his shoulder. The book becomes a bestseller because of the author's charming looks, the vicious nature of the crimes, and his claims of repentance. Lee stages public visits to the homes of family members to beg for forgiveness and even visits Choi at his precinct. Choi, however, dismisses Lee as an imposter. As the media frenzy surrounding Lee increases, family members of the victims gather to plot their revenge, led by Han Ji-soo, whose daughter Soo-yeon was the still-missing 11th victim. They release snakes into Lee's hotel swimming pool, resulting in him getting bitten. The family members then pose as a paramedic unit sent to take Lee to the hospital. They are pursued by members of Lee's security unit, as well as Choi, but eventually get away with an unconscious Lee. Choi recognizes the kidnappers but doesn't inform his colleague. Instead, he tracks down their safehouse and stages a daring rescue, much to the consternation of the family members. Choi leaves Lee in a motel room with a note warning him against making a fuss about the incident. Lee tells the media that the kidnappers were overzealous fans and that he will not press charges. A television station invites Choi and Lee to be on a debate show to discuss the case. During the show, a man calling himself J speaks to Lee over the phone and reveals many personal facts about Choi. J then claims he is the real killer. Choi traces the call. Lee leaves the station and is shot by another family member, resulting in him being hospitalized again. The phone call is traced to Choi's mother's house. There, Choi finds a videotape of the 11th victim Soo-yeon, who was also his girlfriend, being tied up and killed. After scrutinizing the tape, Choi announces in a press conference that it is unclear whether Lee or J is the killer. Lee continues to insist that he is the real killer, and another television debate is arranged between him, Choi, and J to settle the matter. The debate draws thousands of protestors and fans, as well as Han, who carries a pen filled with snake venom, intent upon using it on the real killer. J arrives and directs everyone's attention to a camera crew who finds his 11th victim, Soo-yeon, proving he is the real killer. Lee makes his own revelation, admitting that he is not the killer and he also did not write the book. Lee is actually Jung Hyun-sik, who faked his death with Choi's help and underwent plastic surgery to assume a new identity. They worked together to lure out the real killer, with Choi writing the book with his knowledge of the crimes, and Lee acting as the "face." Although surprised at the elaborate scheme, J claims that Choi cannot do anything to him, as the statute of limitations has long expired. Choi plays the tape of Soo-yeon's demise, revealing the footage was shot in that exact date in 1992, and that he has 14 minutes before the statute of limitations expires. J taunts Choi by saying Soo-yeon carries J's child before her death. The enraged Choi attempts to kill J, but J escapes the TV station, leading to another intense chase scene. Choi finally catches up to J and is stopped short from killing him. As J is escorted away in handcuffs, both Hyun-sik and Ji-soo try to kill him, but Choi stabs J with the pen preventing another person from committing murder. In 2012, Choi is released from prison, greeted by the media and the victims's grateful family members. Due to the case, the statute of limitations was extended to 25 years. == Cast ==