Dong-hyun is a high school student. One day, he falls from the rooftop and bumps into Pan-soo who is a passerby. Pan-soo is a member of a criminal organization. When the two men wake up in the hospital, they discover that they have switched bodies.
High school student Sung Jin commits suicide after being the victim of school violence for a long time. Three years later, one of his bullies Han Yeo Wool debuts as a celebrity. Sung Jin's brother, Sung Hyun, blames himself for not recognizing the pain his brother went through and finds a comment on Han Yeo Wool's news report that Sung Jin didn't commit suicide but was instead killed by Yeo Wool. The brother sets out to find the truth and he heads for destruction.
King Hyeonjong and Kang Kam-chan led the 8-year-long 2nd and 3rd Goryeo-Khitan Wars to victory and began an era of peace in East Asia and prosperity in Goryeo.