Gurus in the late Goryeo dynasty try to obtain a fabled, holy sword, and humans in 2022 hunt down an alien prisoner that is locked in a human's body. The two parties cross paths when a time-traveling portal opens up.

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.

A hitman accidentally kills a little girl. Filled with regret, he wants to quit. But then to tie up loose ends, he is forced to go on another job, to kill the girl's mother.

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.

When an illicit arms deal goes bad, North Korean spy Pyo Jong-seong finds himself targeted not just by the South Koreans but also his own bosses.