Aaliyah, a cleaner hiding her mermaid identity, becomes pregnant after a one-night stand with Lucian, a billionaire werewolf king. They enter a contract marriage to protect the child. Together, they face greedy relatives, a fake princess who steals Aaliyah's designs, and an ancient feud between werewolves and merfolk. When Aaliyah is revealed as the true Sea Princess, Lucian must risk his life to prove his love and unite their warring families.