Serena (Blake Lively) invites Aaron (guest star John Patrick Amedori) to be her guest at a charity gala honoring Lily and Bart (Kelly Rutherford and guest star Robert John Burke), but after discovering a secret that Aaron has been keeping from her she begins to question whether Aaron is the guy she thought he was. Hoping it will help her chances of getting into Yale, Blair (Leighton Meester) naively agrees to babysit the 15-year-old daughter of a prominent Yale donor, but the teenager proves to be more than a handful and Blair begins to suspect that the evening may actually wind up hurting her chances of getting into the college of her dreams. Meanwhile, Jenny (Taylor Momsen) and Agnes (guest star Willa Holland) plan a guerilla fashion show that will either launch Jenny's star or ruin her chances of ever being accepted by the industry.