Ethan Cole, a down-and-out fisherman cast out by his ex-wife, is a "Guardian of the Sea" and heir to the ancient "Children of the Tides" lineage. On the day of his divorce, he rescues Margaret—the founder of a struggling restaurant—at the docks and is subsequently set up with Claire, a driven businesswoman, leading to a whirlwind marriage. Within this contractual union, Ethan makes a stunning impact using his ancestral ability to sense the tides: he harnesses ocean currents and underwater "songs" to pinpoint schools of fish and ventures into the forbidden "Siren's Cove" to harvest rare seafood, turning the restaurant's fortunes around overnight. Facing pressure from a local fishing monopoly and harassment from his ex-wife, the couple unites to fight back; they freely share their fishing techniques with the town's fishermen and ultimately expand the small restaurant into a chain spanning the entire U.S. East Coast.