Shi Yeon (Kim Tae Hee) is a Nine-Tailed Fox living undercover in the human world. She has a dark past when her whole family was massacred, leaving her an orphan. By day, Shi Yeon is an employee at a natural history museum. By night, she's a top-ranking woman warrior in the Nine-Tailed Fox clan, charged with preserving the delicate balance between man and fox. But her world is sent spinning when an atrocious serial murder, where the victims have had their internal organs gouged out is uncovered. Detective Min Woo (Jo Hyun Jae) believes the murders may relate to the organ trafficking trade, and goes undercover in a seedy organ smuggling ring. But Min Woo's cover is blown, and it's only through the intervention Nine-Tailed Fox warrior Moo Young (Jun Jin) and Shi Yeon that he's able to survive! But he's seen their true identities as Nine-Tailed Foxes...can he be allowed to live?