Major crimes unit detective Seong-jin arrests Tae-sung for petty crimes, but shocked to find out that he is the notorious serial killer. However, Seong-jin becomes doubtful of his identity as the serial murder case is investigated.

Ancient Korea, 17th century. While the paranoid King Lee Jo of Joseon, vassal of the Qing dynasty, feels surrounded by conspirators and rebels, a dark evil emerges from the bowels of a merchant ship and the exiled Prince Lee Cheung returns to the royal court, ignoring that he will have to lead the few capable of defeating the ambitious humans and the bloody monsters who threaten to destroy the kingdom.