Spring, 1987. Sung-Jin (Son Hyun-Joo) is an enthusiastic detective with a wife (Ra Mi-Ran) and a son. His dream is to live with his family in a 2 story home. One day, he happens to catch Tae-Sung (Jo Dal-Hwan). He is a suspected serial killer and the first suspected serial killer in South Korea. Due to this incident, Sung-Jin gets involved in a secret operation led by NSP Chief Kyoo-Nam (Jang Hyuk).