It centers on a mentally disturbed woman who becomes obsessed with a man, and assumes a hidden identity in order to apply for the position of a nanny in his home, while she is ultimately determined to be his wife.

Driven by her fascination of romance novels, particularly "The Passion of Mandy", she applies for the job in an attempt to marry James, a similar theme which takes place in her favorite book.

Under a new persona and a new physical appearance, Andrea becomes Nikki Harcourt, as she is told that she bares a strong resemblance to a woman of the same name who used to work with the agency, but has since relocated to Paris.

Nikki is initially rejected for the position, until she kills the successful applicant, Beth O'Reilly, and suddenly moves into the Lewis household, where she is welcomed by the family, including James's teenage daughter, Fawn, and son, Ben.

Fawn decides to do some investigating on Nikki, beginning with a library ticket she found in one of her books, with the name Andrea McBride printed.

It was stated that "Tracy Nelson who does a nice job of bringing out her character's paranoia and unsettled nature which makes her dangerous whilst a little over the top.

Finally, it was said that "What this all boils down to is that "The Perfect Nanny" is just your routine delusionally obsessed young woman drama where she is capable of killing to try and get her way.