Wang So (Jang Hyuk) is the Prince of Goryeo who has a cursed fate. He had to get married with the Last Princess of Balhae, Shin Yool (Oh Yeon Seo). She was born with the fate of becoming the light for another country. But because of this fate, she has to face death. Through their marriage life, Wang So and Shin Yool begin to grow closer and love each other.