In the fictional utopian nation of Yuldo, established by the righteous bandit hero Hong Gil-dong, Jeon Woo-chi is a dosa, a Taoist wizard, who gained his powers by swallowing a gumiho fox bead. A friend's betrayal causes him to lose his mentor, and sorcery turns the love of his life Hong Mu-yeon into an emotionless assassin. So in order to avenge them, he travels to Joseon, and is moved by the plight of the people and becomes a reluctant hero to them.