Hyun-jin and Tae-hyung are at odds from the moment they meet, only to discover that they will soon be in-laws.

The in-laws who have been at odds are forced to live together with their orphaned nephew, Woo-joo.

As they navigate caring for Woo-joo, Tae-hyung makes an irresistible proposition to Hyun-jin and proposes cohabitating for a month.