In the third-season opener, Serena returns from Europe with Carter while Nate returns from abroad with a mysterious woman (JoAnna Garcia). Elsewhere, Blair and Chuck adjust to their new relationship in a nontraditional way, and the Humphreys are surprised at how easily they adapted to the Hamptons lifestyle.
Blair, Dan and Vanessa begin their first day at NYU, where Georgina sets out to make Blair an outcast. Elsewhere, Chuck and Serena have a big fight, and Nate and Bree pursue their relationship, despite the strain it may cause their families.
Blair and Chuck compete against each other when bidding for a coveted item up for auction. Elsewhere, Serena fears Carter is returning to his old bad habits; Vanessa grows suspicious of Scott; and Georgina sets her sights on Dan.
Vanessa gets a new roommate: film star Olivia Burke (Hilary Duff), who seeks a normal college life. Serena befriends Olivia's costar Ursula (Tyra Banks). Elsewhere, Jenny begins her reign as queen bee and gets some unwanted help from Blair; and Lily finds her return home unsettling.
Lily and Rufus push up their wedding date. Meanwhile, Chuck realizes Carter has been keeping a secret from Serena; Dan and Vanessa get roped into one of Georgina's ploys; and Blair shares her suspicions about Bree with Nate. Sonic Youth perform.
Vanessa hopes to impress her mother (Gina Torres) by delivering NYU's freshman toast, but she has to compete with Blair to win this honor. Meanwhile, Dan introduces Olivia to Lily and Rufus, and Serena and Nate join forces to help out Carter.
Chuck requests Serena's PR assistance for the grand opening of a club in his new hotel, and Blair secretly assists him as well. Elsewhere, Dan is rattled when he watches one of Olivia's on-screen sex scenes; Jenny's friendship with Eric faces an obstacle; and Rufus and Lily celebrate Halloween. Albert Hammond Jr. performs.
Nate worries about how far his grandfather will go to help Trip win an election. Meanwhile, Olivia tries to prevent Dan from hearing something she regrets saying on Jimmy Fallon's show; and Blair befriends a new It Girl to make Serena jealous.
A power-hungry Jenny eyes a cotillion escort who could help her expand her reign to all of the Upper East Side. Elsewhere, Nate and Chuck try to get Blair and Serena to make amends; and Olivia considers leaving NYU to shoot a movie, much to Dan's dismay. The Plastiscines perform, and Leighton Meester and Robin Thicke's single "Somebody to Love" is featured.
Blair attempts to impress her classmates by getting Lady Gaga to agree to a private concert. Meanwhile, Dan, Olivia and Vanessa get involved with a school play; Serena leans on Nate for help; and Jenny befriends an ambassador's son as a favor to Chuck.
Thanksgiving dinner becomes uncomfortable for Serena when Lily invites Trip and his wife to attend. Meanwhile, Blair thinks her mom is keeping a secret from her; Rufus discovers Lily has been lying about Cece; and Vanessa has a fight with her mother.
A year after his father's death, Chuck deals with an issue from the past, and another car accident occurs on the Upper East side. Meanwhile, Dan and Vanessa face the new complexities in their friendship; and Jenny gets accused of assaulting a classmate.