In 1453 Prince Su-Yang kills Kim Jong-Seo to eventually become the 7th king of the Joseon Dynasty.  One year before the coup, Kim Jong-Seo (Lee Soon-Jae) is the most powerful liege and the most trusted by King Moon-Jong (Jeong Dong-Hwan). King Moon-Jong becomes sick and his brother Su-Yang (Kim Yeong-Cheol) plots to take the king's throne. King Moon-Jong to ward off his brother, joins forces with Kim Jong-Seo to protect the next king, Prince Dan-Jon.  Kim Seung-Yoo (Park Si-Hoo) is Kim Jong-Seo's youngest son. He is smart, good looking and the son of one of the most powerful families in the country. Seung-Yoo likes to drink alcohol with his close friends. In the palace, Kim Seung-Yoo becomes a teacher for Princess Kyung-Hye (Hong Soo-Hyun).  Lee Se-Ryung (Moon Chae-Won) is the eldest daughter of Prince Su-Yang. She hears talks of an impending arranged marriage for herself with Kim Seung-Yoo and becomes curious about her possible future husband. Se-Ryung pretends to be the Princess Kyung-Hye and takes a class in her place. That is a secret between Se-Ryung and Princess Kyung-Hye. Se-Ryung's first meeting with Seung-Yoo doesn't turn out to be a good experience.  By chance, Seung-Yoo watches Se-Ryung losing control of a horse she is riding. The horse runs towards the edge of a cliff. Seung-Yoo saves Se-Ryung before tragedy ensues. Because of this incident Seung-Yoo and Se-Ryung become close.  Meanwhile, in order to protect Princess Kyung-Hye and Prince Dan-Jong from the king's brother Su-Yang, King Moon-Jong asks Kim Kong-Seo if Princess Kyung-Hye and Seung-Yoo can marry. Kim Jong-Seo accepts and, consequently, turns away Se-Ryung. Unaware of the arranged marriage, Seung-Yoo and Se-Ryung become even closer.  Princess Kyung-Hye is astonished that she will marry Seung-Yoo and not Se-Ryung. She begins to feel jealousy over their close relationship. Su-Yang learns of the proposed arranged marriage and sends assassins to kill Seung-Yoo before the marriage takes place. Su-Yang is unaware that his own daughter Se-Ryung is with Seung-Yoo.