A woman from London starts working for a family as a nanny and discovers that the mother thinks she has an imaginary child called Maggie.

When Annie (Rita Wilson) and Tim Beeman (Victor Garber) hire Gillian (Tushka Bergen) as a nanny, she accepts the job with the understanding that her most important responsibility is the middle child, Maggie --- an imaginary child created by Annie. Maggie is loved and acknowledged by everyone in the family. Tim and the eldest daughter, Doc (Mae Whitman), play into the charade for the sake of Annie's sanity. Unsteadily, Gillian begins to care for the imaginary Maggie, but she becomes concerned for the youngest child, Sam (David Dorfman), who believes that he has a sister he cannot see. She also worries about the responsibility Doc has taken upon herself to maintain her mother's fantasy. Torn between her love for the family and her uneasiness with the situation, Gillian contacts the authorities unbeknownst to the Beeman family. Soon after, Tim explains to Gillian why the family endures Annie's fantasy and why they care for Maggie. When Children Services comes to the Beeman home to question the family's situation, Gillian regrets her decision to contact the authorities.

A woman with two children believes that she has three, and her husband and their firstborn play along with her to keep her balanced (or as close to balanced as a woman with an invisible child can be). However, when the family hires a new nanny, it is all just too much for her and she starts to blab.—John Sacksteder <[email protected]>

Annie 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 and her husband 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. The nanny's involvement helps facilitate Annie's separation from the imaginary child and a return (we assume) to a normal family existence.—Anonymous