This drama is about the criminal investigations that based on the real “Hwaseong serial murder case“.

20 years ago, Father of Ha Moo Yum (Yoon Sang Hyun)was a suspect in the “Gap Dong” serial murder case. Because of the detective’s oppressive investigation, Moo Yum’s father killed himself.

After 20 years, Moo Yum become a detective and works to find the realkiller. The statue of limitations has expired for this serial murder case and Moo Yum decided to resign because he believe that the killer already dead. However, New clues appears…