Time is A.D. 927, when Georan invaders have conquered the ancient Korean capital of Balhae and set up a new country, Dongran-guk. The leaders of Balhae desperately need a royal figure to reunite their nation. They find a prince, the previously exiled Dae Jung-Hyun (Lee Seo-Jin), who's hiding out under the name So-sam.
The leaders dispatch a peerless swordswoman, Yeon So-Ha (Yoon So-Yi), to protect So-sam before Georan's Killer Blade Army, commanded by Gun Hwa-Pyung (Shin Hyun-Joon), finds him first. Initially, he sends his deputy, Mae Young-Ok (Lee Ki-Yong, to handle the situation: She wants to become the greatest swordswoman of the age and knows she must first kill Yeon So-Ha.
