Chen Youyu, a poor seafood stall owner, accidentally signs a Sea Registry employment contract while gathering seafood along the shore and becomes a Sea Patrol Officer. He gains the abilities to breathe underwater and locate top-quality seafood. Teaming up with Mo Bing, a trainee clerk who is actually a little octopus, he gathers and sells fresh seafood to pay off his outstanding fees and break into the high-end market, all while facing competition from Luo Jingui. Eventually, he transforms his little stall into Chen's Fresh Seafood, while Mo Bing earns a permanent position guarding the human world.