Nereid Ione gives birth to a moon-crested baby in a dungeon. The royal family deceives her, claiming the infant died and sealing its soul. Forced to stand in for Princess Daphne as the tribute bride to demigod Theron, she has no choice but to obey to protect the trapped soul.
Theron has spent a year searching for the mysterious woman with the silver crescent mark, his long-lost lover. He raises a baby boy named Elio, unaware of the truth. At Theron’s palace, Ione’s endless divine milk and her unique bond with Elio make her question everything.
As hidden feelings stir between the two, the wedding day arrives. Theron’s ex-fiancée Medea bursts in, claiming to be Elio’s mother with the same crest. When Ione’s matching mark is exposed, Theron is stunned. Just as secrets surface, Elio calls Ione "Mama". Who is the real mother? What fates await them all?
