21-year-old Annie Braddock (Scarlett Johansson), has just graduated from Montclair State University. Annie has no idea what or who she wants to be. One day, while sitting at the park, Annie sees a young boy about to be hit by a vehicle. Annie saves him and meets the boy's mother, Mrs. Alexandra X (Laura Linney). 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.