Xiao Wei (Zhou Xun) is a fox spirit (狐狸精) that feasts on human hearts in order to maintain her lovely, youthful appearance. When General Wang Sheng (Chen Kun) 'rescues' her from a band of bandits and brings her home, trouble brews as the demon falls in love with the general, who is married to Pei Rong (Zhao Wei).
Another older love triangle is present, between the general's brother Pang Yong (Donnie Yen), Wang Sheng, and his wife. Pei Rong asks Pang Yong for help as she suspects Xiao Wei for what she really is. Pang Yong is aided by an inexperienced 'demon hunter', Xia Bing (Betty Sun). Hints of a developing relationship between Xia Bing and Pang Yong are there, although this is never fully explored. Another subplot revolves around Xiao Wei's demon ally (Qi Yuwu), who is actually morphed from a lizard, and who also has unreciprocated feelings for Xiao Wei and helps her obtain all the human hearts she needs.