As summer draws to an end, Blair and Chuck continue to adjust to being in a relationship with one another. Serena returns from Europe with new secrets to hide and a new relationship with Carter Baizen. Nate also returns from vacationing and brings home a mysterious girl, Bree Buckley. Meanwhile, Rufus, Dan and Jenny spend the summer in the Hamptons and learn to adjust to the van der Woodsen's glamorous lifestyle.
The Upper East Side is thrown for a loop when Gossip Girl reports that Serena van der Woodsen, Manhattan's most notorious party girl, has arrived back in town after a mysterious absence where no one knows where she was or why she left. Not even Serena's closest friend, Blair Waldorf, knew her whereabouts and is shocked to learn Serena has returned. However, their once close friendship is complicated upon Serena's return, strained now that Serena is the center of attention and Blair has been cast from the limelight, and the revelation that Serena had a fling with Blair's boyfriend Nate Archibald.
Also ruling the Upper East Side is Chuck Bass, son of the wealthy and powerful Bart Bass and a friend of Nate's since childhood. Chuck leads a reckless life, which often leads Nate down a similar path of darkness and destruction.
Lastly there's Dan Humphrey and his sister Jenny, middle-class kids on the outside looking in on the exclusive wealthy clique. Dan and Jenny are forced to attend the school by their former rock star father, Rufus, who has a tumultuous past with Serena's mother Lily van der Woodsen, a socialite with a secret past as a groupie. However, Dan and Serena's worlds collide following a chance meeting where Dan quickly finds himself dating the girl of his dreams. The closer they become, the more Dan learns about the real Serena and how different she is from the world in which she lives.
With all of the ever-changing drama in the lives of the teenagers and adults alike, the ever-present Gossip Girl is always around to keep up on the complex and intriguing world.