Based on the ancient legend of the mermaid's tears, this film combines fantasy martial arts elements to tell a story about desires that produce original sins and grievances. Jiang Tianyang, the son of the head of Kunlun Sect, is determined to seize the position of the head, and for this purpose, he practices the evil Yuanxu Dafa. He joins hands with the mermaid Luo Xi to kill back to Kunlun Sect for revenge, but finds that right and wrong are reversed, and good and evil are reversed. He also became obsessed with practicing evil skills and was controlled by the villain. In order to save his lover, Luo Xi sacrificed himself and used the last mermaid's tear to dissolve Jiang Tianyang's evil skills. This film uses several reversals like Rashomon to express the view of the opposition and unity of right and wrong, good and evil, and that extreme paranoid emotions will lead to tragedy. The protagonist in the story went from seeking revenge for the throne at the beginning to realizing that greed would produce original sin and growing into a chivalrous knight, reflecting the hero's mental journey of growth. The heroine in the film put aside her hatred at the critical moment, sacrificed herself to help the hero save the crisis, and sang the main theme of love of tolerance, selflessness, dedication, etc. in the tragedy.