Nanny, the name of the main character, first encounters her employer, Mrs. X, in Central Park. She is hired nearly right away. Nanny’s duties include picking Grayer up from school, dropping him off at his many lessons (French, music, swimming, physical education, etc.), and keeping Grayer out of his mother’s way. In the elevator of Mrs. X’s apartment building, Nanny meets Harvard Hottie, a student at Harvard, who she develops a crush on. The crush is put on ice when Nanny meets H.H.’s friends who insinuate that she, being a nanny, must be sleeping with Mr. X and H.H. says nothing.
Nanny is infinitely patient with Grayer and knows how to coax him into listening to her. Her job is made more difficult, however, when Mrs. X starts treating Nanny as a personal assistant. Nanny does everything Mrs. X asks without question. This includes putting on a purple Teletubby costume for Mr. X’s Halloween office party. At the party, Nanny takes Grayer stumble on Mr. X and one of his employees, Ms. Chicago, in a darkened office. Grayer observes that Ms. Chicago is not wearing any pants.
Soon it’s Valentine’s Day and Mrs. X gets all dressed up and ready to go to dinner with Mr. X, who’s flying in from Chicago. He’s an hour late and Nanny suggests Mrs. X watch the news to see if there are any flight delays. Manwhile, Mr. X calls Nanny and tells her that his flight has been delayed and he’ll call Mrs. X tomorrow. Just as he hangs up, Mrs. X reports that the weather is fine and Nanny should call Mr. X to ask where he is. Nanny at first says Mr. X’s meeting ran long and he’ll have to stay in Chicago. Mrs. X asks Nanny to repeat exactly what Mr. X said and Nanny does so. Thus, Mrs. X knows Mr. X is cheating on her.
Mr. X’s clothes are being packed by the maid, Connie, when Mrs. X decides Connie is unreliable because she has misplaced Grayer’s bowtie. As Connie is preparing to leave, Connie warns Nanny that Mrs. X is selfish, jealous, and petty. She fired Grayer’s first nanny because the nanny found a boyfriend and couldn’t work weekends. Then Connie shows Nanny a pair of lace panties she found under the bed in the master bedroom, presumably belonging to Ms. Chicago.
H.H. and Nanny have reconciled and H.H. tells Nanny that Mr. X was married before and Mrs. X broke up that marriage much the same way Ms. Chicago is doing now. Nanny feels sorry for Mrs. X but Mrs. X is acting cold toward Nanny now that Nanny knows about Mr. X’s affair. When the family prepares for a vacation in Nantucket, Mrs. X is peeved that Nanny won’t be with them from the first day. Nanny explains that she is graduating that day but Mrs. X is indifferent.
In Nantucket, Nanny overhears Mrs. X telling another parent that she has installed a nanny cam recently. Nanny is outraged but doesn’t say anything. Mr. X suddenly says he is needed back at the office but Mrs. X has invited Mr. X’s mother and now Mr. X can’t leave. The next day at a BBQ, Mr. X is seen with his arm around another woman. That evening, Nanny asks Mr. and Mrs. X if she can go home a day early because her roommate has kicked her out of her apartment. Mrs. X ignores this at first and announces to Mr. X that she is pregnant. Nanny tries to back out of her request but Mrs. X suggests that if Nanny is in such a rush, she can leave immediately since she is obviously not devoted to Grayer. Nanny says she wants to stay the night so Grayer doesn’t wake up alone but Mrs. X insists that Nanny leave without saying goodbye.
As Nanny is leaving, she feels compelled to tell Mrs. X that Ms. Chicago has been in her home. Mrs. X angrily denies the possibility. Grayer wakes up as Nanny is leaving and begins screaming for Nanny, but Mrs. X pushes Nanny out the door. Back in New York, Nanny goes back to Grayer’s home and finds the nanny cam. She tapes a message to Mr. and Mrs. X and returns her house keys knowing she’ll never see Grayer again.