Ean has a critical mission to return to the future to save everyone. However, she becomes trapped in the distant past while trying to prevent the escape of alien prisoners who are locked up in the bodies of humans. Meanwhile, Muruk, who helps Ean escape various predicaments, is unnerved when he begins sensing the presence of a strange being in his body. Traveling through the centuries, they are trying to prevent the explosion of the haava.

An aging assassin with a knack for taking out society's worst encounters a young protégé eager to learn the trade. As they form an unlikely bond, the veteran killer discovers fresh purpose in her twilight years of violence and routine.

An action historical drama depicting the story of Joseon's best swordsman Yi Nan in front of an irreversible fate.