Fisherman Tong Shan unexpectedly passed away, reborn and possessing the body of a black dog, retaining human memories, and being reborn with the obsession to protect his wife and children. He activates the Divine Dog System, relying on beachcombing and hunting to accumulate evolution points to grow stronger. His stepmother and elder brother are harsh and greedy, oppressing the orphan and widow. The black dog strongly protects his wife and daughter, catching rare seafood such as green crabs and abalone, leading the whole family out of poverty. A deep-sea shark king breaks into the offshore waters, and sea pirates plunder seafood, plunging the fishing village into crisis. The black dog saves people at the risk of his life several times. In the ultimate battle, he and the shark king fall together into the abyss, swallow the millennial blood coral, break free from the dog's body to restore his human form, and walk back from the sea to his wife's side. This family is finally reunited.