During the chaotic period of Ming-Qing dynasty transition, after failing to protect and preventing the downfall of Gwanghaegun, Tae-yul, the best swordsman in Joseon, lives in seclusion with his daughter Tae-ok in the mountains. As Tae-yul's eyesight begins to fail due to an old injury, Tae-ok seeks to find a treatment for him. Tae-ok is King Gwanghaegun's daughter whom Tae-yul is protecting.