To raise lifesaving money for his younger sister, fisherman Shen Yanchao goes out to sea to catch fish with his fiancée and childhood friend, only to be betrayed. The two lock him in an iron cage at the seabed waiting for him to die. At his last gasp, he unexpectedly meets the mermaid princess Canglan, and the two conclude a "sea pact", granting Shen Yanchao the ability to command all things in the ocean! Returning to dry land, Shen Yanchao relies on sea beasts to guide him, frequently catching deep-sea rare treasures like mutated blue lobsters and single-head abalones. Not only does he pay off his debts and cure his sister, but he also wins the favor of female CEO Xu Qingtang, embarking on a path of skyrocketing wealth. Taking over his family's abandoned fish pond, human and fish cooperate with tacit understanding, transforming this abandoned mud pit into a top-tier ocean ranch.