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.

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

As Yoon-seong discovers Hyun-jin's secret, Tae-hyung learns that Yoon-seong was her first love.

Tae-hyung gets assigned to work with Hyun-jin and Yoon-seong, while Hyun-jin learns of Tae-hyung's true feelings.

Tae-hyung is shaken by the sudden appearance of his estranged father. Meanwhile, Hyun-jin struggles at work.

Hyun-jin finds herself torn between Yoon-seong and Tae-hyung.

Having learned the truth about his past, Tae-hyung decides to leave Hyun-jin and Woo-joo for their safety.

As Hyun-jin grows closer to Yoon-seong, Tae-hyung keeps his distance and decides to move abroad.

Hyun-jin reunites with Tae-hyung after realizing her feelings for him, but their day out is disrupted when Woo-joo goes missing.

As Woo-joo's guardianship hearing approaches, an unexpected incident threatens to tear the family apart.