Lee Yeju can escape death by walking through a "door" leading to the near future. But unfortunately, this time, the door she walks through drops her a thousand years later. To make matters worse, she runs into a magical madman who wants to destroy all humans. She gets away by going through the door again, but strangely, it keeps leading her right back to him. It seems like the only way for her to survive is to follow this man, but can Yeju prove to him that there's still hope for humanity?