Upon learning that their parents are selling the family home, irresponsible Kate and her straight-laced sister return to their hometown to clear out their old childhood bedroom. Discovering the house is already sold, the bickering siblings decide on one final hurrah: recapturing their past glory by throwing a massive high-school-style blowout for their now-grown classmates. In the process, Kate and Maura trade their customary roles, sending the night spinning completely out of control. Now the wild party threatens to bring the house down in ruins, forcing both women to confront their real-life adult problems.