Ancient southern China. After battling the Ice Witch (Vivian Hsu), who has sworn eternal vengeance against all men for their unfaithfulness, Buddhist monk Fa Hai (Jet Li) imprisons her soul in Leifeng Pagoda, where his pupil Neng Ren (Wen Zhang) is also based. Meanwhile, two sisterly snake demons, the white Bai Suzhen (Eva Huang) and green Qing (Charlene Choi), are surveying the human world at their leisure when Bai rescues young herbalist Xu Xian (Raymond Lam) from drowning and both fall for each other. Qing is annoyed at Bai s love for a human, but agrees to tag along with her as they both change into female form to find Xu Xian again. In the meantime, he has met Fa Hai and Neng Ren, who are hunting down vampire-bat demons that have been causing death and destruction in the region. All five meet up in a canal town during the Lantern Festival, during which Fa Hai and Neng Ren fight some vampire-bat women but fail to kill their leader, the Bat Demon. Next morning Neng Ren wakes up to find he s starting to change into a bat after being bitten during the battle, so Qing, who s come to like him, reveals she s a demon too. However, Fa Hai lets both Bai and Qing know that he will not tolerate demons and humans falling in love, and he ll kill both of them unless they disappear.