Three years after a revolution brings down the royal dynasty, a princess who has been imprisoned underground is ordered by the emperor to enter a political marriage with a powerful duke. Haunted by the judgment of others, she repeatedly retreats into the darkness she has created within herself. Through the love and bond they build together, she gradually learns to face her true self and discovers that promises and trust can be stronger than fate, and that they may have been each other’s long-awaited return all along.