There's a scene in The Perfect Man in which a teacher asks a student the meaning of the phrase, "Oh what a tangled web we weave, when first we practise to deceive". As the young student offers his interpretation, another classmate, Holly Hamilton (Hilary Duff) - oblivious of the question and the answer - plots the next stage of her own increasingly elaborate deception. And, yes, she does ensnare herself in escalating lies.
Tired of moving from place to place and school to school every time her mother, Jean (Heather Locklear) is dumped by her latest boyfriend, Holly decides to invent the ideal admirer for her romantically challenged mum. Relocated to New York following Jean's most recent love letdown, Holly and her seven-year-old sister, Zoe (Aria Wallace) have become conditioned to the fact that their new home will probably be just temporary accommodation if their mother has her usual run of bad luck with a relationship.
At school, Holly finds a new friend, Amy (Vanessa Lengies) who introduces her to her uncle, Ben (Chris Noth), a good-looking restaurant owner who also seems to know exactly what women want romantically. Holly takes notes and starts concocting a secret admirer for her mother - first by sending her orchids (the perfect flower according to Ben) and then by beginning e-mail correspondence that soon has her mother falling for the phantom lover Holly has invented. Things start to get really knotty when Holly sends Jean a photo of Ben - who is totally unaware of the "affair" he has been having on the net.
Meanwhile, mum, who works in a bakery where she decorates kitschy cakes, is being pursued by Lenny (Mike O'Malley), a sincere, but kind of dopey co-worker who is so smitten by her that the desperate Jean thinks he may turn out to be her ideal man. After all, Ben - as good as he sounds - is not someone she has actually met. But that could soon change. Holly's plans go completely off the rails when her mother announces she is meeting friends at a restaurant.