A sexual scandal between a math teacher and a student in a prestigious high school ended in tragedy. 4 years later they meet again, now as adults, to reveal the corruptions in school and to regain one's reputation as a teacher.

Kong Ji Hyeok works as the leader of the Mother TF team at a baby products company. He is sharp, calm, and executes passionately. One day, a team member, Ko Da Rim, suddenly kisses him. This places him in a difficult position because she is a married woman.

Meanwhile, Ko Da Rim is a single woman who needs a job to support herself. She gets a job as a temporary employee at the baby products company where Kong Ji Hyeok works. She lies about her background and states she is married with a child to get hired there. She now works under Kong Ji Hyeok on the Mother TF team. Her only interest is to become a permanent employee there, but she begins to have feelings for Kong Ji Hyeok.