The Joseon palace is overrun with powerful female ghosts and evil spirits, all of whom harbor deep grudges against the royal family. Unfortunately, government officer Yoon Gab (Yook Sung Jae) becomes possessed by an Imugi, a mythical shapeshifting serpent-like creature. This brings Yeo Ri (Kim Ji Yeon), a young woman from a family of shamans, into the palace in an attempt to cure Yoon Gab, forcing her to confront her family's legacy – and her former love. Meanwhile, the dreams of reformist monarch King Lee Sung (Kim Ji Hun) are disrupted by the strange and terrifying events unfolding within the palace. Yeo Ri must put aside her reluctance to inherit her fate and team up with Yoon Gab and the King to restore order to the kingdom before vengeful spirits manage to take over!