Summer in the Hamptons lives up to it's usual reputation. Serena and Blair are muses to a famous designer who brings in two copycat, cheaper versions of Serena and Blair as models. They crash parties, run into Nate naked and make him even more confused than ever.
Jenny is living it up in Prague with her mother, Jeanette Humphrey, looking at art galleries and preparing for her new life. At the same time, Serena's eighteenth birthday is a night of revelations and regrets, but who will end up with whom? And will the now-graduated seniors ever recover from their summers?