If one can make a Naga mermaid cry, the shed tears will turn into priceless luminous pearls. Hai Shi is a young girl living in a coastal village where people use the ruse of killing their children to make mermaids cry and gather the pearls to pay for taxes. It was on such a fishing trip that Hai Shi's father was killed. Hai Shi's town was ransacked by soldiers and she develops a grudge against the emperor whom she holds responsible for the tragic events and vows to seek revenge. She then meets Fang Zhu who is an official of the imperial court and the emperor's closest confidant. Fang Zhu offers to accept Hai Shi as a disciple on the condition that she hides her true identity and poses as a boy. She accepts the terms. The kingdom is in peril due to a self-indulgent and apathetic ruler, unrest in court, and constant conflict with neighboring kingdoms and only held together by Fang Zhu's sheer determination. Years pass and Hai Shi joins the royal military. Her feelings for her master and their opposing sentiments towards the emperor become a matter of conflict while secret plots and schemes threaten the very fabric of their kingdom.