Mars dealt with the murders in a criminal investigation drama motif iltan the murders.
1996, 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.
But 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 cop 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.