Kim Tae Hyun is a promising young surgeon, but his finances take a dive when his sister's health condition requires costly dialysis treatments. When Tae Hyun subsequently falls into a vicious cycle of debt, he assumes the alias of "Yong Pal" and begins making house calls for criminals who are willing to pay top dollar. Complicating things further, Tae Hyun gets involved with Han Yeo Jin, a comatose patient at the hospital.

Kingdom of Goguryeo, ancient Korea, 645. The ruthless Emperor Taizong of Tang invades the country and leads his armies towards the capital, achieving one victory after another, but on his way is the stronghold of Ansi, protected by General Yang Man-chu, who will do everything possible to stop the invasion, even if his troops are outnumbered by thousands of enemies.