During the Northern Song Dynasty, the prosperous and peaceful times made Kaifeng Prefecture gradually become a mere formality. Zhan Zhao (Andy Lau), who followed Bao Zheng (Anthony Wong), missed his chivalrous life in the past because he had nothing to do all day and fantasized about wearing black clothes again one day. During one of his actions to become someone else, Zhan Zhao met the golden-haired mouse Bai Yutang (Cecilia Cheung) and was deeply attracted by his words and deeds. The Five Rats made a riot in Kaifeng Prefecture and took away the engagement token between Zhan Zhao and the sister of the King of Xiangyang (Li Bingbing). Zhan Zhao was ordered by the emperor to chase the Five Rats to Xiankong Island to persuade them to surrender, which attracted Bai Yutang, who was originally a girl, who was just beginning to fall in love. However, because Zhan Zhao was under the imperial marriage contract, the two could not be in love, but their fate did not end there.