Zhang Xiao is fresh out of college. One day, she comes across a man and his baby daughter. When the baby calls her "Mommy" and clings to her, she doesn't know what to do. Mu Chen, the father, finds the situation even more baffling because his daughter has never called anyone that. He asks Zhang Xiao to become his daughter's nanny and hands her a contract. A professional/personal relationship begins, while dark secrets from the past, while Mu Chen minds himself caught in a dilemma as her daughter grows closer to her nanny.