Hyun-joon, an ordinary office worker who believes that housework, especially childcare, is naturally a woman's lot, wakes up one morning to the cries of his son Sang-ah. His wife has decided to leave home, feeling that just staying home taking care of children is a waste of her own life. From that day on, with nowhere to leave the baby immediately, Hyun-joon carries Sang-ah in front of him in a modern way and goes to work with a diaper bag. The rigid office experiences a small commotion due to the newborn, but gradually, colleagues get used to the baby crib and the crying in a corner of the office, and Hyun-joon also becomes skilled at feeding the baby, changing diapers, preparing baby food, and calming the baby. Meanwhile, Young-joo, the only woman in the office, looks after Sang-ah when Hyun-joon is late for entertaining Japanese clients, and from then on, the feelings between Hyun-joon and Young-joo become subtle. Young-joo realizes that Hae-seok, a man with perfect conditions, is only meeting her out of possessiveness and gives up the life she had planned with him. Then, realizing that her love for Hyun-joon and Sang-ah is special, Young-joo returns to them.