Gap-dong

Gap-dong is a 2014 South Korean television series starring Yoon Sang-hyun, Kim Min-jung, Sung Dong-il, Kim Ji-won and Lee Joon. It aired on cable channel tvN from April 11 to June 14, 2014 on Fridays and Saturdays at 20:40 (KST) for 20 episodes.

The series is based on the real-life Hwaseong serial murders.

Synopsis
In 1986, the (fictional) city of Iltan in Gyeonggi Province: A young girl gets brutally murdered by an unknown person on a dark night. As the city is gripped by a succession of serial killings, a total of nine murders within a twelve-kilometer radius since 1993, the police conclude that a man they've nicknamed "Gap-dong" is behind the crimes. Detective Yang Cheol-gon is convinced that the actual killer is Ha Il-sik, a resident of the town who is intellectually challenged. His attempt to arrest the suspect fails as Ha commits suicide to prove his innocence. His death inspires his son Moo-yeom to become a police officer to clear his father's name and restore his honor.

Seventeen years later, Moo-yeom is a police detective who spends his career chasing dead ends and helping juvenile delinquents. After the statute of limitations on the case expires, Moo-yeom becomes resigned to the belief that Gap-dong is dead. But then a series of incidents occur in the town that bear an eerie resemblance to Gap-dong's crimes. Cheol-gon, now a well-decorated officer, has recently transferred back to Iltan, and to his dismay, Moo-yeom joins his investigation team to catch Gap-dong once and for all.

Main

 * Yoon Sang-hyun as Ha Moo-yeom, a detective in Iltan Police Department's violent crimes unit. He vows to avenge his wrongly accused father.
 * Kim Min-jung as Maria Oh, a psychiatrist with a mysterious double life and a suspicious curiosity for all things Gap-dong.
 * Sung Dong-il as Yang Cheol-gon, a police inspector at the time of the original murders, and is now a well-decorated officer. Upon receiving his latest promotion, he surprises his superiors by requesting to be assigned back to Iltan, because he wants to end his career by capturing Gap-dong. Still convinced that Moo-yeom's father was the killer, he is extremely prejudiced against Moo-yeom, which makes for a combative working relationship. He also hiding grief of his daughter's death.
 * Kim Ji-won as Ma Ji-wool, a 17-year-old high school student and webtoon artist with the pen name "Matilda". Ji-wool becomes pivotal to the case when her webtoon titled The Beast's Path ends up foretelling the crimes. When she becomes the killer's next target, it also serves as a set of clues to find him.
 * Lee Joon as Ryu Tae-oh, an inmate of a prison psychiatric hospital, who becomes a barista after his release. With a genius IQ of 150, his excellent and detailed memory may prove valuable to cracking the case, but he also happens to have the disposition to be a dangerous psychopath, and considers Gap-dong his god and hero.

Supporting

 * Jung In-gi as Cha Do-hyeok, the police section chief. He was in fact, the true culprit of the "Gap Dong" serial murders. He was sentenced to death nearing the end of the series
 * Hyun Woo as young Cha Do-hyeok
 * Kang Nam-gil as Han Sang-hoon, a profiler
 * Jang Gwang as Jinjo, a monk
 * Choo Soo-hyun as Oh Young-ae
 * Lee Seung-ho as Kim Shin-yong
 * Yoo Eun-ho as Yang Seon-joo, Cheol-gon's daughter
 * Lee Go-eun as young Seon-joo
 * Min Sung-wook as Nam Ki-ri
 * Jung Won-joong as Park Joong-goo
 * Jang Hee-soo as Kim Young-mi, Maria's mother
 * Yoon Kyun-sang as the youngest detective
 * Seo Cho-won as Supporting
 * Hong In-young as Hong Sung-hee, a reporter
 * Seo Joo-hee as Ji Hwa-ja, Ji-wool's mother
 * Jo Ji-hwan as Lee Hyung-nyeon, Moo-yeom's partner and wife

Ratings
In this table, the blue numbers represent the lowest ratings and the red numbers represent the highest ratings.


 * This drama airs on a cable channel/pay TV which normally has a relatively smaller audience compared to free-to-air TV/public broadcasters (KBS, SBS, MBC and EBS).

International broadcast

 * It aired in Thailand on Workpoint TV beginning March 9, 2015.
 * In Hong Kong, Macau, Sri Lanka and Southeast Asia, the drama began airing on tvN Asia with a variety of subtitles on 2016.