On her coming-of-age day, the three brothers who once vowed to love Min Si-eun for life break their promise. Heartbroken, she forms a marriage pact with Woo Do-hyun, the Abyssborn prince who has loved her for years, and leaves for Abyssreach. Only then do her brothers realize they've lost her. But it's too late. Do-hyun protects Si-eun more tenderly than anyone, while the brothers belatedly try to prove their love and win her back.
