The son of Kim Yu Sin, the skilled and handsome Won Sul leads the Silla army on an expedition. However, due to the stratagems of a Tang general and the betrayal of the vanguard commander Dae To, he suffers a crushing defeat, loses his men, and returns severely wounded. Accused of violating the Hwarang code of not retreating from the battlefield, he is disowned by his father and wanders the mountains. Driven by the humiliation of defeat and the despair of exile, he attempts suicide, but the love of Jindallae, a Goguryeo maiden, restores his strength and resolve. Won Sul executes the traitor and returns triumphantly with the enemy general's head. With the king's permission, he marries Jindallae.