The Tang dynasty's naval fleet has been devastated by a sea monster and it is not long before a young Dee Renjie is investigating the case. He also attempts to prevent the sacrifice of the beautiful courtesan Yin Ruiki. Mystery adventure prequel, starring Mark Chao, Carina Lau and Feng Shaofeng. In Mandarin.

Young Dee Renjie arrives in the empire's capital to join the Supreme Court as police judge of his region. He wants to become a prosecutor. Empress Wu, who is at the beginning of her reign, has commissioned the fierce detective Yuchi to investigate a sea monster that stalks the city at night and makes it unsafe.