When the scholar Jeong Yak-jeon is exiled to Heuksando Island during the Catholic Persecution of 1801, he decides to write a fish-based encyclopaedia.
After being blinded in a coup against the king, Joseon's greatest swordsman goes into hiding, far removed from his city's anguish. But when traffickers kidnap his daughter, he has no choice but to unsheathe his sword once more.