The story is about Lena (Gigi Leung), Johnny (Lau Ching Wan) and Wayne (Louis Koo) who are commissioned to devise a promotional campaign for a baby product line named "Mighty Baby". New to his managerial post, Johnny employs the always-nervous Sabrina (Rosemund Kwan) as his secretary. Knowing that her boyfriend Wayne is "baby-phobic", Lena seeks help from Boey (Cecilia Cheung), a child psychologist. Wayne at first does not trust Boey in her expertise, but as times goes by, he notices her strong points and her charm...