Jang Nan-gam is a competent detective who has to catch not one but two serial killers. In A Killer Paradox, Son Suk-ku plays Jang Nan-gam.
When Nan-gam was young, his father took every opportunity to bully him. He was never affectionate; instead, he would always take out his frustration on his son.
One day, Nan-gam stopped giving him the reaction he sought, and he stopped bullying Nan-gam. He lost the power he had over Nan-gam.
Nan-gam learned his lesson that day and went on to become a police detective, as he did not want anyone to look down on him.
Chasing Tang and Song Chon
When Nan-gam investigates the cases of Lee Tang’s victims, he starts suspecting Tang, even though there is no evidence against him.
Nan-gam is good at his job. He is able to notice details and make connections that others miss, which is how the police uncover Yeo Bu-il’s identity.
Nan-gam’s instincts also lead him to Roh Bin. His suspicions about Roh Bin’s involvement with Tang are later confirmed.
However, Roh Bin manages to provoke him into being aggressive with him on live stream, which results in Nan-gam getting suspended.
Despite his suspension, Nan-gam continues chasing Tang, and that is when he finds out that Song Chon, a serial killer he failed to catch in the past, has returned.
Nan-gam’s father was also a police detective. Years ago, he was injured by a junior detective, who turned out to be none other than Song Chon, which left him brain-dead on life support.
Nan-gam also found out that his mother was having an affair with Song Chon. When Nan-gam became a detective, he was approached by Song Chon’s partner, Roh Bin.
Roh Bin believed that Nan-gam was the only detective capable of apprehending Song Chon, who had turned into a serial killer.
However, as he didn’t share all the information he possessed with Nan-gam, Song Chon managed to escape.
Nan-gam has not moved on from his failure to capture Song Chon. He still hopes to bring him, as well as Tang, to justice one day.
Emotional closure
Nan-gam’s junior is injured while trying to catch Song Chon, which leaves Nan-gam distressed. As Nan-gam knows the most about Song Chon, he is reinstated to pursue him.
Roh Bin approaches Nan-gam once again, offering information on Song Chon. However, Nan-gam does not trust Roh Bin and refuses to let him use him once again.
Later, when Song Chon kills his father, Nan-gam decides to go after Song Chon. To find him, he has no choice but to agree to Roh Bin’s terms.
Nan-gam finally succeeds in killing Song Chon, but not before Song Chon reveals to him that his father was a corrupt cop and that his mother was having an affair with his father’s best friend, not with Song Chon.
As per his deal with Roh Bin, Nan-gam lets Tang choose between turning himself in or running away, but not without warning him that he will eventually get caught.
Although Nan-gam avenges his father, he has to face the consequences of taking the law into his own hands. He gets suspended once again.
Meanwhile, Nan-gam’s junior recovers. Additionally, with his father’s passing, Nan-gam is relieved of the weight of making the decision to remove him from life support.
While Nan-gam no longer carries emotional burdens, the chapter with Tang is far from over. Tang has returned home, and the killings of criminals resume once again.