Park Kwang-ho is a policeman in a criminal case squad. Living in 1986, he is investigating a serial homicide. However, the case is blurred and the number of victims is increasing. The police is clueless. While tracking the suspect to a tunnel, he is attacked. When he wakes up, he is surprised to find himself in the year of 2016 and accidentally replaces a police officer with the same name born in 1988. So Kwang-ho stays in 2016 to continue his "hunting journey”....