On the night of the sacrifice, village girl Elena is thrown into the deep as the sea's chosen bride—but instead of drowning, she wakes in the pearl-and-coral palace of Caspian, the merfolk king. She soon discovers the kingdom's hundred-year curse is a lie: Morwen, the royal advisor, is the witch who has ruled the deep through a fabricated bloodline, and the glowing spiral on Elena's arm is the true mark of the Sea God's heir. Framed for poisoning the king, exiled and hunted, Elena awakens her heritage, rallies the outcast tribes, and returns for the final battle. When Morwen unleashes the ghosts of a hundred sacrificed brides, Elena does not destroy them—she sets them free, proving that lost things can come home. The witch is taken by the tide she tried to steal, the sacrifice system is abolished forever, and Elena ascends the throne—not as a queen of fear, but as the daughter of the tide, rebuilding a kingdom where sea and shore live as one.
