When Serena (Blake Lively) notices that Dan (Penn Badgley) has been cozying up to the new girl in school, Amanda (guest star Laura-Leigh), the ever-loyal Blair (Leighton Meester) and her minions decide to befriend Amanda and sabotage her budding new romance with "lonely boy." Vanessa (Jessica Szohr) discovers a scandalous secret about Catherine (guest star Madchen Amick) and enlists Blair's scheming expertise to use the information to help Nate (Chace Crawford). Meanwhile, Lily (Kelly Rutherford) finds herself drawn back to her ex, Rufus (Matthew Settle), once again. Taylor Momsen and Ed Westwick also star.