Twenty-one-year-old Annie Braddock has just graduated from Montclair State University. She has no idea what or who she wants to be. One day, while sitting in the park, Annie sees a young boy about to be hit by a vehicle. Annie saves him and meets the boy's mother, who we meet as Mrs. X. When she introduces herself as "Annie", Mrs. X mistakes her words for "Nanny" and hires her to look after Grayer, the boy she saved. Annie lies to her mother about taking a job at a bank and, in reality, moves in with the X's to be the nanny for Grayer. Life with the incredibly privileged X's is not what she thought it would be, and her life is complicated further when she falls for "Harvard Hottie", who lives in the building. Interspersed with her life as the X's nanny are her interactions with "Harvard Hottie" as well as her longtime friend Lynette. She continues to keep her mother in the dark about her real job, giving her regular but false progress reports. Further complications arise when her mother decides to visit her, forcing Annie to pretend Lynette and her roommate are a couple and that their apartment is Annie's apartment. Her mother finds out the truth when Grayer becomes severely ill, and Annie desperately calls her for help. After a rough start, Annie eventually bonds with Grayer, whom she addresses by his preferred code name, "Grover", and discovers that he is actually a sweet and loving child who is neglected by both his parents, which explains his uncontrollable behavior. Parallel to this, Annie begins to also notice that Grayer is not the only one being neglected: Mrs. X is as well, with Mr. X constantly being cruel to her and committing subtly obvious adultery. Mrs. X makes numerous attempts to make her husband love her, including lying to him about being pregnant with their second child. Annie soon realizes that Mrs. X's own cruel treatment of her is due to Mrs. X's growing frustrations from her dysfunctional marriage. Things take a turn for the worse during a family trip with the X's to Nantucket. She overhears Mrs. X telling a friend during a party that she has installed a "nanny cam" at their home in the city and plans to fire Annie after viewing footage showing Annie lovingly tending to Grayer. The next morning, Mr. X sexually assaults Annie just as Mrs. X enters the kitchen. She unreasonably fires Annie and sends her back to the city with her final payment of just $40—along with a puppy Mr. X had given Grayer when they arrived in Nantucket but foisted off on her as she was leaving. Flying into a rage, she looks for and finds the "nanny cam" in the X's house and records her feelings toward the X's. Mrs. X brings the tape to the school meeting for the Upper East Side mothers. Thinking that the tape will show Annie feeding Grayer peanut butter and jelly, she requests the coordinator to play it for everyone to see. All other parents in the room hear as Annie reveals the real relationship between the X's, in the process making Mrs. X come to terms with her own reality and false happiness. Annie continues to date "Harvard Hottie", whose real name is revealed to be Hayden. She is temporarily living with Lynette and her roommate, and pursuing her growing interest in anthropology, much of which she learned through her time as the X's nanny. A few months later, Hayden hands her a letter from Mrs. X. Written in the letter is an apology and news about how Mrs. X left Mr. X, is raising Grayer alone and making stronger attempts to bond with him, and Grayer's overall improvement. She expresses her gratitude to Annie for waking her up and changing her life. Also in the letter, Mrs. X addresses Annie for the first time by her real name, and signs the letter with her own first name, Alexandra.
As of September 1, 2007, the film had an average score of 46 out of 100 on Metacritic based on 33 reviews. On Rotten Tomatoes, 34% of critics gave the film positive reviews based on 128 reviews. The consensus view was that the film had a "miscast lead and unrealistic, one-dimensional characters make this class satire far less effective than it should've been." The film was released in the United Kingdom on October 12, 2007. The film opened at #6 at the box office in the United States, and earned $7.4 million in 2,629 theaters in its opening weekend. As of November 23, 2007, the film had grossed $25,918,399 domestically and $21,807,447 overseas for a total worldwide gross of $47,738,099 against a $20 million budget.
