Shy vet, Dr Abby Barnes (Janeane Garofalo) is a radio question-and-answer host on a local radio station in her spare time, leading the show "The Truth About Cats and Dogs".
However when she unwittingly woos a listener by her soothing tones and personailty, she is in a quandary as to what to do when Brian (Ben Chapman) asks her out.
On arriving at the radio station one day to try and meet Abby, Brian mistakenly bumps into Abby's, decidedly non-intellectual bestfriend, model Noelle (Uma Thurman), and thinks that she is infact the Abby from the show.
Instead of clearing things up straight away, the highly self-conscious Abby allows her best friend, Noelle Slusarsky, a tall, stunning blonde, to take her place for a while after she has a crisis of confidence about her looks. To carry this off affectively, Abby takes on the made-up persona of Donna, while thinking Brian would never go for her anyway because she is a short, cute, brunette, who thinks she's unattractive.
Now a bizarre love triangle develops as the women go to increasingly desperate lengths to hide the truth as the real Abby woos Brian over the phone and radio, Noelle, the pseudo-Abby, takes her place in the flesh.
As time goes on, Abby feels more and more confident that Brian would rather have the beautiful Noelle than the simply attractive Abby.