In ancient Korea, three legendary warriors—Deok-gi, Seol-rang, and Poong-chun—aspire to overthrow a corrupt ruler. They share a dream of justice and equality, forming a strong bond rooted in trust and shared purpose. However, betrayal and ambition tear them apart as Deok-gi, driven by his personal desires, turns against his comrades to seize power for himself. This act of treachery leads to Poong-chun's death and leaves Seol-rang severely wounded but alive. She flees with Poong-chun's infant daughter, Hong-yi, vowing revenge on Deok-gi.

Years later, Seol-rang, now blind and living in seclusion, trains Hong-yi in martial arts, preparing her for the day she will confront Deok-gi and avenge her father's death. Hong-yi grows into a formidable swordswoman, determined to fulfill her mother's vengeful mission. The underlying tension is set against a backdrop of historical strife as old alliances resurface and long-buried secrets begin to unravel. The story navigates through themes of betrayal, loyalty, and the harsh consequences of seeking revenge, with dramatic confrontations that explore the complexities of honor and forgiveness.