Seong-jin (SON Hyun-joo) is a major crimes unit detective loyally working for his country by catching criminals. As an ordinary head of household, Seong-jin's wish is to live a decent life in a two storey Western-style house with his beloved wife and son. While working day and night to catch criminals, Seong-jin arrests Tae-sung, a criminal suspect, and gathers circumstantial evidence which suggests that this suspect could be Korea's first serial murderer. Following this incident, Seong-jin unwittingly becomes deeply involved in the confidential cover-up scheme led by Gyunam (JANG Hyeok), the Investigation Division Head at the National Intelligence Agency. Meanwhile, Freedom Daily's reporter Jae-jin who is close with Seong-jin like family, senses something suspicious about the case while covering the story. Jae-jin tells Seong-jin that it would be best to take his hands off the case. However, having been promised of surgery for his son's crippled leg, Seong-jin accepts Gyu-nam's uncomfortable offer. This choice he had to make as a father instead puts Seong-jin and his family in greater danger and his whole life is shook up.
