Twenty-eight-year-olds Seon Tae-hyung and Woo Hyun-jin find their lives upended when they are forced to raise their infant nephew, Woo-ju, following the sudden death of the child's parents. Despite being in-laws with no prior close relationship, the two begin living together to care for the baby. As the inexperienced pair navigates the challenges of parenthood, they grow closer and begin to develop romantic feelings for one another.