Set in the Joseon Dynasty period (during the confusion of justification and the period of espionage and transition from ming to ping), when public desire for social reform was at a high.
The three-arc historical action-romance drama, in which warriors and spies step back and forth along borders, follows Crown Prince So Hyeon, his two bodyguards, Heo Seung Po and An Min Seo, as well as Park Dal Hyang, a yangban come warrior who has everything going for him, including personality and looks, even though he comes from a poor family. Dal Hyang is also involved in a love triangle between Yoon Seo, the Crown Princess, and Crown Prince So Hyeon. Meanwhile Jo Mi Ryeong is Prince So Hyeon's first love, who later becomes the prince’s enemy and decides to take revenge.