The story begins in the childhood of Kwon, a boy destined to be known as the warrior who protects Goryeo. Kwon and his older brother Jeong are the sons of Man Jeok, a slave who was also the strongest martial artist in Goryeo. When Man Jeok leads a failed slave rebellion and is executed, the brothers find their lives in constant danger.

While hiding and training in their father’s martial arts, they are ambixed by masters. Jeong is killed, and Kwon barely escapes. He loses consciousness and wakes up inside a cruel colosseum in the Song Dynasty, a brutal region where only the strong survive. To avenge his brother, Kwon vows to become the strongest warrior and return home to kill the monster responsible.