The future Seoul, a city with the worst environmental pollution and the highest living prices. Shin-dong, the protagonist of the film, is helplessly living a repetitive and monotonous life, and is forced to find a new place to rent immediately by his landlord's unilateral notice. Unable to afford to move, his friend tells him that renting out a part of the house will complicate his rights and making it impossible for the landlord to evict him. Encouraged by his friend's advice, Shin-dong puts up an ad for rent. And when a strange newlywed couple shows up who want to live in the bathroom, Shin-dong impulsively invites them in.