At the Emerald Green Lake is a romantic fairy tale.
A poor scholar, Jeung Jan, had been betrothed to Peony, the Prime Minister’s daughter. The Prime Minister was not happy with the pre-arranged betrothal and was hoping to find some excuses to dissolve the engagement.
The Prime Minister sent Jeung to live in a hut next to the Emerald Green Lake. It was in this lake where the Fairy Golden Carp resided. Every night, Jeng talked to the golden carp about his misery. The Fairy came to know Jeung and felt sorry for him. One day she transformed herself into the form of Peony, Jeung’s fiancée, and tried to cheer him up. They fell in love.
Eventually, it was discovered that there were two look-alike Peonies.
The Minister was unable to tell which one was his daughter, so he sent for the famous judge in the capital, Judge Baau, to come and help.
The Fairy beat the Prime Minister’s plan by asking Fairy Turtle to transform himself into Judge Baau to help her out. Now the problem became more complicated than before since there were not just two look-alike Peonies, but two Judge Baaus as well. The case could not be solved, so Judge Baau asked the immortals for help.
書生張真與丞相之女牡丹幼訂婚約， 張真不幸親亡家敗， 投奔金府， 丞相不悅， 借口”三代不招白衣女婿”, 命他于碧波潭畔草蘆攻讀， 張真朗朗書聲， 感動了碧波潭中鯉魚精， 她變作牡丹與張真相會， 天長地久， 兩情漸深。
一日張真誤遇厭貧重富之真牡丹， 被誣為盜， 趕出金府， 鯉魚精聞訊趕來， 道明真相， 張真愛其情真意摯， 品格高尚， 不嫌異類， 決定攜她同返家鄉， 結為夫婦。 不料途中又被丞相捉回。 于是兩個牡丹， 真假難分， 丞相請包公來審案， 鯉魚精也命龜精變成包公， 兩個包公， 自然無法斷案。 丞相又請天神捉妖， 鯉魚精眼看敗北遇險， 幸逢觀音前來救助。 但她不願為仙隨歸南海， 寧願忍痛拔鱗， 貶落凡塵， 一雙志誠男女， 終于締結良緣。