In an imaginary world, modern-day Korea is run by a constitutional monarchy facing crumbling popularity after the recent death of the reigning King. To try to help the situation, the Royal Family decides to marry off the Crown Prince, Lee Shin (Joo Ji Hoon) prior to his ascension to the throne. To their horror, however, they discover that the dead King's father, Shin's grandfather had a pact with a commoner that their grandchildren would marry. Enter headstrong, klutzy, Shin Chae Kyung (Yoon Eun Hye), an average girl who is now suddenly engaged to the country's Crown Prince.
Among the plots, deceptions, and expectations in the mix, can the Royal couple see each other for who they really are and manage to fall in love?