 Annie (Rita Wilson) is the mother of two children who has created an invisible third child for reasons not exactly known to her family or the audience. Her eldest child (Mae Whitman) and her husband (Victor Garber) aid her in this fantasy to avoid a breakup of the family that is sure to happen if anyone learns about Annie s delusions. Perhaps sensing the dysfunction of her fantasy and the effect it s having on her youngest child (who sincerely believes he has an invisible older sister), she hires a nanny (Tushka Bergen). The nanny s involvement helps facilitate Annie s separation from the imaginary child and a return (we assume) to a normal family existence.