After returning to his seaside fishing village, college student Chen An faces the debts left behind by his deceased older brother and the difficult life his sister-in-law, Su Qin, has been struggling to support on her own. Determined to repay the debts, he decides to head out to sea to fish. Unexpectedly, on his very first fishing trip, he rescues an injured giant shark and gains a mysterious ability to communicate with his shark doppelganger and share its underwater perspective. From then on, while others rely on luck to gather seafood along the shore, Chen An uses his shark doppelganger to explore the depths and hunt for treasure. Coral trout, wild giant freshwater prawns, and enormous deep-sea creatures appear one after another. He helps his sister-in-law turn their lives around and grow wealthy, but his success also attracts the jealous schemes of fishmongers, business owners, and malicious villagers. Faced with oppression and attempts to seize his gains, Chen An refuses to back down. Using his shark doppelganger, he sweeps the seabed for its riches and protects his family.