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.

As Hyun-jin and Tae-hyung's relationship deepens, Hyun-jin hides their living arrangement from her first love, Yoon-seong.