Joseon-Era, around 1633. Lee Gyeom is the son of the virtuous nobleman Lee Won-ho, who is the king's trustworthy supporter and brother, and a central member of the secret organization Cheonwoohoe, composed of other five important nobles with the king as their leader. When a blind fortune teller, looking at Lee Won-ho's home, refers to the king that he sees a person as bright as the sun who would be adored by the people, the king killed Lee Won-ho as he believed that 'two suns cannot exist on the same sky'. Gyeom, from the inside of a safe, manages to survive and witnesses the murder; later, when he is forced to throw a rock at his mother's head to prove that he isn't her son, he loses his memory for the shock and is adopted by a retired thief, Soe-dol, who renames him "Yong". Thirteen years later, Yong regains his memories and begins to search for his older sister Yeon, only to see her being sentenced and hanged.