Tak Dong-kyung (Park Bo-young), an editor for a web novel company, lives a fairly ordinary life until she stumbles into an unexpected fate. All in a single day, she finds out she is dying from glioblastoma and has only three months to live, learns that her boyfriend is a father-to-be and has a wife, gets scolded by her superior at work, and is spied on by a pervert before the pervert falls into a sinkhole.
Drinking her problems away, she happens to see a shooting star from her rooftop apartment and drunkenly wishes for the world to be doomed. Her wish is heard by Myul Mang (Seo In-guk), a messenger between gods and humans. He was born between dark and light: when he breathes, countries disappear; when he walks, the seasons collapse; when he smiles, a life is extinguished. All he has to do is exist for something to fall into ruin. This is not his intention but simply his fate. On his birthday, he gets to choose a human's wish to fulfill. Sick of his fate, he choses to fulfill Dong-kyung's wish to end the world.