The drama is about a fictional Goryeo-era prince who is first in succession for the throne. He belongs to a royal secret society, and is dogged his whole life by a prophecy that he will turn Goryeo into an ocean of blood someday. His character is meticulous and bold, and is especially good at making quick decisions on his feet. The heroine is the last princess from Balhae (there are only eight years of overlap in these two kingdoms), and is skilled in many areas, including astronomy, geography, and the art of war. She’s fated to bring light to the Goryeo prince, and she’s described as spunky and wise, and a believer in fated love. The drama will depict their palace romance, between a cursed prince and a princess of a lost nation.