East China Sea Heavy Industry heir Lu Xiao is betrayed by his fiancée and sworn brother. Pushed into the sea, he binds with the Deep Sea Dominator System, transforming into water to exact his revenge. Behind-the-scenes mastermind K leads multiple factions in a encirclement campaign; ancient sea beasts, chaebols, and higher-dimensional enemies arrive one after another, turning a personal vendetta into a war for civilization's survival. Researcher Lin Qian chooses to assist Lu Xiao. Lu Xiao sacrifices his divine body and ultimately merges with the ocean origin, repelling the invaders. He remains permanently in the deep sea to guard the waters, while Lin Qian oversees the marine ecosystem on land, restoring balance between humanity and the ocean.