Marni and her older brother, Will, go to high school together. Little does Will know that Marni is bullied everyday by a girl name Joanna.
Flash forward a few years, Marni has ditched the braces and bangs, and has a job in New York. She is flying home because Will is getting married!
Marni finds out that Will is actually marrying Joanna, her high school enemy. But when she finally talks to Joanna again, Joanna acts like she doesn't remember her.
Marni tries to get Will to know who the real Joanna is so she does a series of things that try to break Will and Joanna break up.
At the wedding, Marni plays a video of Joanna from high school that shows everyone the old Joanna and she has Joanna's ex-fiancee come give a speech. Will gets mad and doesn't talk to either Joanna or Marni.
In the end, everyone forgives each other. They decide people can change and that Will and Joanna are meant to be together, so they actually have another wedding!