Christina has an older sister who is not only a saintess but also the crown prince's fiancée. Christina deeply loved her sister, who had cherished her in place of their mother, who passed away when Christina was young. However, one day, her sister's engagement was suddenly broken off. Her sister was to be dispatched to the enemy nation with whom they were currently in a truce, and at the same time, Christina’s own engagement to the crown prince was announced. Several days later, Christina received the report that her sister had died, plunging her into despair. However, by a strange turn of events, she learns that the royal family was involved in her sister's death. Trembling with anger, Christina resolves to take revenge on the royal family by using her fiancé, the crown prince. And so, she joins forces with a cold-blooded duke who also harbors a grudge against the royal family, and their magnificent revenge drama begins───!