Song Da Eun or better known as Diana Cavanagh as her english name, is the leader of the most powerful underground organization called the Shadows. She is known to be death and life at the same time for she had beauty, brains, money that no once could compare but is as deadly as death itself. Her parents are the wealthiest and most successful business man and woman. She can do everything, and an expert at that; fighting, leading, doing business, fashion even killing, but not love. 

To Diana, love is petty, a weakness and will only end in pain and chaos of the heart. But what happens when EXO's Baekhyun, needs protection from her? What happens if the only way to protect Baekhyun is to marry him? Will she accept him and find that love is not what she perceives it to be? Diana will face her most challenging trial yet.