"The Mermaid Beauty" tells the enchanting tale of a carp spirit, Xiao Lian, who finally achieves human form after 500 years of cultivation. She finds herself deeply involved in the human world through her kind friend, Mudan, who is betrothed to the poor scholar Zhang Ziyou. Their love is threatened by Mudan's father, who intends for her to marry the General's son, Jiang Yunfei, for status. Seeing Yunfei's cruel nature, Xiao Lian champions Mudan and Ziyou's bond, secretly arranging their meetings.
However, Yunfei uncovers their secret and orchestrates a vicious plot, framing Ziyou for attempting to violate Mudan, leading to his unjust imprisonment. Enraged by this injustice, Xiao Lian works tirelessly to expose Yunfei's lies. Tragically, Mudan falls gravely ill, believing Ziyou to be dead and consumed by grief. In a desperate final effort to unite them, Xiao Lian attempts to steal Mudan from her wedding, but fate intervenes, and Mudan perishes.
Determined to bring happiness to Ziyou, Xiao Lian assumes Mudan's identity, leading them to a carefree life in the mountains. Her vibrant spirit and playful nature bring joy and teach Ziyou to embrace life's simple pleasures. This newfound bliss is shattered when Ziyou discovers Xiao Lian's true identity, accusing her of murder and condemning her as a demonic spirit. Simultaneously, the relentless Taoist Zhang Tianshi hunts for demons, including Xiao Lian's mother who possesses the Yuanping Pearl. The film explores whether Ziyou can ultimately accept Xiao Lian for who she truly is.
Other names: Legend of Heaven and Earth - The Beauty Mermaid, Tian Di Chuan Shuo Zhi Yu Mei Ren, Legend of Heaven and Earth: A Natural Mermaid Beauty, 天地传说之鱼美人