Female salvage diver Nerine brings the handsome Halden, whom she just fished out of the sea, back to her engagement yacht, only to catch her fiancé Leontes cheating with her stepmother Mireva. After her father's death, Mireva has been controlling Vale Corporation, ousting Nerine from the management and forcing her to take on only the most dangerous diving work; Leontes, too, regards their engagement as nothing but a tool to seize her shares. The story flashes back twelve hours earlier: Halden is the young CEO of Tidebound Port Group who has just returned from overseas, coming back this time to reclaim the ancestral port that has been occupied by the Vale family for years. Learning that this formidable rival is back, Leontes orders his men to secretly get rid of him. His men push Halden into the deep sea, then falsely report that he has been reduced to nothing but bones at the bottom of the ocean, never expecting that Nerine would rescue him during a salvage operation.
Furious, Nerine calls off the engagement, and asks Halden, whom she believes to be an "ordinary engineer", to pose as her new fiancé so they can stop Leontes from taking over the company together. Halden stays while temporarily hiding his identity, uses his professional expertise to help Nerine win back projects and the fleet, and makes her, who has long been looked down upon, gain respect for the first time, as the two gradually fall in love. To drive Halden away, Leontes keeps blockading the docks and cracking down on the fleet, forcing Halden to directly reveal his hidden identity as a billionaire CEO and mobilize the Tidebound fleet to strike back forcefully. Nerine later learns that Halden also came back to seize the port, mistakenly believing he has been using her feelings, and breaks up with him in anger. Leontes takes the opportunity to seize control of Vale Corporation and mobilizes a large salvage ship to destroy the dock. Nerine and Halden team up again to stop the disaster: Leontes eventua