Eight months pregnant, Shen Qingli has her life-saving pregnancy tonic stolen by her husband, Gu Zhiwen, who uses it to nourish Xiao Yu, a mermaid, until she transforms into human form. In the end, both Shen Qingli and her unborn child die. Reborn on the day the mermaid enters her home, she pretends to comply while secretly switching the medicine, setting up surveillance cameras, and joining forces with her childhood sweetheart, Fu Sihan, to expose her husband's plot to seize her family's fortune. As the mermaid's transformation begins to backfire, the alliance of greed between Gu Zhiwen and Xiao Yu gradually falls apart. Shen Qingli ultimately saves her child, reclaims her family business, and ensures that both conspirators are punished. She also discovers that behind her rebirth lies Fu Sihan's profound love: he traded ten years of his life to bring her back.