A mermaid ventures the human land in search for the Moonstone, a sacred merfolk artifact, and the lost monarch of the Boundless Sea.

After witnessing the massacre of her family on her wedding night, Xie Lanqin returns to lead the Liansheng gang and seeks justice. With the support of her stepson, she uncovers hidden truths and faces dangerous trials, ultimately working with her former fiancé to uncover the truth and find their way back to each other.