After going bankrupt, seafood business owner Lin Fan returns to his hometown with his daughter, Doudou, and the spirit dog Dahuang. By chance, he obtains a dragon pearl that allows him to sense the deep sea, see through the seabed, and breathe underwater. Members of the Black Tide organization, including Tide Mother, covet the dragon pearl and the Red Scale, which can awaken the ancient sea. They experiment on children using their spiritual meridians. Lin Fan and his daughter join forces with Dahuang and a special investigation team to fight the villains, overcome challenges in the deep sea, resolve the Red Scale contamination crisis, and protect their family and the peace of the entire sea.