Zhang Zhen (Kwan Chi-bin)'s beautiful flute attracted Hong Ling (Zhao Liying), a carp spirit in the sea. Taking the opportunity to select a birthday gift for the Dragon King, she came to the amazing human world and met Zhang Zhen, who had met her once before. Zhang's father Wenxiang (Cheng Hong) and the prime minister's sister Jin Ruolan (Bai Shan) have been in love for many years. Hong Ling and Zhang Zhen intend to match this pair of lovers. Unexpectedly, Zhang Wenyang was murdered by bad guys on the eve of the wedding. The guard Zhan Feng (Ding Zijun) assisted Zhang Zhen in tracking down the murderer of his father, and Tang Xin (Cao Xinyue), a playmate who had a crush on Zhang Zhen, followed the investigation. Jin Mudan (Dai Jiaoqian), the daughter of the prime minister's favorite, was betrothed to Zhang Zhen since childhood. However, Mudan was arrogant and wanted to marry into the imperial family. She looked down on the poor scholar Zhang Zhen. Witnessing this scene, Hong Ling transformed herself into Mudan and talked about love with Zhang Zhen. Who knew that they would fall in love over time and fall in love. Jin Mudan, who was determined to climb up the social ladder, never dreamed that Zhan Feng, a fourth-rank guard in the capital, was actually the crown prince Zhao Duan whom she had been thinking about day and night...