A brutally murdered girl was found dead in a park near a subway station in Seoul. Eight years passed, but the culprit has not caught. Detective Kang, who was in charge of the case, repeats the days of suffering and nightmares from guilt. On the eighth anniversary of the murder, a popular news host and the famous announcer killed. Soon, a dead woman's head delivered to the Seoul Metropolitan Police Department. A series of murders targeting women surfaced. A task force to catch the murderer initiated. Detective Kang, who is still suffering from past events, feels that those crimes are somehow connected with him and begins an independent investigation.