As he passes the Jing River while he is on his way to the imperial examination, scholar Liu Yi sees a shepherdess crying her heart out in the open country. The woman, Sanniang, is the daughter of the dragon king of Lake Dongting. After marrying the prince of the Jing River, Sanniang has been constantly abused by her husband and her parents-in-law. Moreover, they have stripped her of her mystical power of flight and left her destitute. Indignant, Liu has decided to give up the examination to deliver a letter disclosing her miseries to her father at Lake Dongting.
Having received his daughter’s letter, the dragon king ponders what action to take. Meanwhile, the dragon king’s brother, Qiantang, explodes when he hears what has befallen his niece. Qiantang immediately mounts a war against the prince, who has no remorse for what he has done to his wife, and kills him. After the war, Sanniang reunites with her parents. Grateful to Liu and admiring his noble character, Sanniangoffers a loving toast to Liu at a banquet. The dragon king attempts to unite the two. However, unwilling to be seen as a wife-stealer, Liu rejects her love flat. Disappointed, Sanniang sees Liu off.
Back home, Liu’s mother tries to find a match for her son. However, since Sanniang is always on his mind,Liu finds none of the candidates appealing. Learning of this, Qiantang has Sanniang turn herself into a fisherman’s daughter and himself into a matchmaker. Finding the girl pretty and diligent, Liu’s mother prevails upon her son to marry the fisherman’s daughter. On the wedding night, Sanniang triumphantly reveals her true identity, and the opera comes to a happy ending.