In the year 2022, a Robot Guard (Kim Woo-bin) manages alien prisoners trapped inside human brains. Raising the young girl Ean on Earth, he lives in the guise of a human being. One day, when an alien prisoner escapes, the entire planet is thrown into jeopardy and Guard goes back to the past with Ean to trap the alien there. Meanwhile 631 years earlier during the Goryeo Dynasty, an older Ean (Kim Tae-ri) is known as "The Girl Who Shoots Thunder". While Ean is trying to retrieve the Divine Blade, the key to traveling through time, Muruk (Ryu Jun-yeol), a hapless dosa (Korean tao magician), is aiming to claim the enormous bounty placed on it. Also setting out on a desperate scramble to obtain the Blade are the Sorcerers of the Twin Peaks, Madam Black (YUM Jung-ah) and Mr. Blue (JO Woo-jin), and the masked Jajang (KIM Eui-sung).Can Ean find the Divine Blade and stop the alien before it's too late?