During the reign of Emperor Tianxiang in Dazheng, the tax on pearls was heavy. Ye's father asked Ye Haishi to go to the sea to lure the merfolk to the surface in order to get enough pearls for the tax. When the merfolk, Lang Huan, gave Haishi a box of pearls, the cruel officials wanted to take the pearls for themselves and destroyed the village. At the critical time, Ye Haishi was saved by Fang Zhu. She became Fang Zhu's second apprentice as a boy and changed her name to Fang Haishi. During her years with Fang Zhu, Fang Haishi learned all her skills, being able to protect the peace of the Dazheng and achieving battle achievements. She got feelings for Fang Zhu after experiencing many dangers. But Fang Zhu was unable to respond because of his mission of guarding Emperor Xu and Dazheng. Later, Fang Zhu was forced to reveal Haishi's identity as a woman to protect her, and sent her to Emperor Xu. The relationships between them became complicated.