As the summer draws to a close in the Hamptons, Serena and Nate have everyone fooled into thinking they are a couple to cover up the fact that Nate has been hooking up with a married, older woman (guest star Madchen Amick). Blair returns from abroad with a hot guy on her arm (guest star Patrick Heusinger), making a very jealous Chuck (Ed Westwick) question his decision to leave Blair stranded at the heliport. Dan has spent the summer assisting a famous author (guest star Jay McInerney). While interning for Eleanor Waldorf's company, Jenny sneaks an invite to a much-coveted Hamptons' White Party at which Eric introduces her to socialite Tinsley Mortimer.

Blair is over the moon that she is dating royalty and has every intention of becoming a royal herself, but a scheming Chuck has other plans for Blair and her new love, Marcus, when he introduces Blair to Marcus' stepmother who happens to be Catherine. Meanwhile, Nate learns the downside to having an affair with Catherine when he keeps getting caught in his lies and learns his family has gone bankrupt due to his father jumping bail.

In a humorous twist, Blair questions the lack of passion in her relationship with Marcus, while at the same time Chuck appears to have lost his "passion" for any woman other than Blair. Meanwhile, Nate struggles between his feelings for Vanessa and his more-complicated-by-the-day relationship with Catherine. Jenny risks losing her internship when Eleanor catches Jenny critiquing one of the Eleanor Waldorf designs.

Blair and her minions decide to befriend the new girl, Amanda (guest star Laura-Leigh), in order to sabotage her possible new relationship with Dan. Vanessa discovers a scandalous secret about Catherine and enlists Blair's scheming expertise to use the information to help Nate. Meanwhile, Lily finds herself drawn back to her ex, Rufus, once again.

In the midst of Fashion Week, a furious Blair learns that her mother, Eleanor, at the suggestion of her protege Jenny, has given Serena and her new socialite friend, Poppy Lifton (guest star Tamara Feldman), front row seats to the Eleanor Waldorf show. Hurt once again by Serena's popularity and her mother's betrayal, Blair decides to sabotage the show. Meanwhile, Dan starts hanging out with Chuck, but a walk on the dark side always has its risks and Dan learns that the hard way. Lily learns a secret that her new husband, Bart, has been keeping from her.

After Blair and Serena get into a catfight, Serena decides to get even with Blair, who has always dreamed of attending Yale, by ditching her plans to visit Brown, and instead accepting the Dean of Yale's personal invitation to visit the school. After discovering that none of his recommendation letters for Yale were ever submitted, Dan frantically tries to figure out a way to salvage his chances of getting into the school. While on the Yale campus, Chuck is kidnapped by a group of Skull and Bones members and Nate hooks up with a co-ed.

Vanessa uses the scandalous picture of Catherine and Marcus to blackmail Blair into being a nicer person, so Blair seeks revenge by enticing Chuck to seduce Vanessa. Lily and Bart throw an extravagant housewarming party and expect their children to make them proud in front of the attending press, but a rebellious Serena isn't ready to play by their rules. Meanwhile, Dan and Jenny discover a big secret that Nate has been keeping from his friends.

Jenny befriends a young model, Agnes (guest star Willa Holland), who encourages Jenny to not only explore her wild side, but also confront her boss, Eleanor Waldorf, who is attempting to "borrow" Jenny's designs. Serena meets an artist, Aaron Rose (guest star John Patrick Amedori), and realizes they have an instant chemistry. Blair attempts to seduce Chuck, but it proves tougher than she ever imagined.

Serena invites Aaron to a charity event, but soon uncovers a secret Aaron has been keeping from her. Thinking it will help her get into Yale, Blair agrees to babysit the 15-year-old daughter of a Yale donor, but her plan quickly backfires. Meanwhile, Jenny and Agnes plan a fashion show.

Blair sets out on a mission to break up her mother and Cyrus Rose, her new man. Jenny moves in with Agnes as the two continue with their plans for their own fashion line. As Serena continues to fall for Aaron, she learns something that may derail their relationship forever while Dan interviews Bart Bass for an article for New York Magazine.

It's Thanksgiving time and Blair is offended when her Mom's new man hijacks her Thanksgiving traditions. Lily attempts to strengthen the frail bond between Rufus and Jenny. Eric discovers a secret about Bart. Vanessa and Chuck help Nate deal with his father.

As the annual Snowflake Ball approaches, Blair and Chuck make a bet that they can find the perfect date for one another. Aaron's ex-girlfriend, Lexi, becomes attracted to Dan, creating mixed feelings for Serena.

The entire Upper East Side of Manhattan is rocked when Bart Bass dies suddenly in a limo accident. Serena and Eric take the news very calmly while Lily has a troubling time despite her mother, Cece's, awkward attempts to comfort her. Chuck begins to blame Lily for his father's death and threatens to reveal a secret that Bart found on her before his accident. Meanwhile, Blair's mother, Eleanor, prepares for her latest marriage to Aaron's father Cyrus.

Because Chuck is MIA since his father's funeral, his Uncle Jack arrives on the Upper East Side to find and help him. Trying to forget her last conversation with Chuck, Blair focuses on being accepted into the most prestigious ladies club in the city, Colony Club. Jenny returns to Constance Billard and immediately takes on Penelope and her posse of mean girls, but no one is going down without a valiant Gossip Girl-worthy fight.

Chuck, Jack and Lily come together for the reading of the will which reveals what will come of the Bass empire. Rufus and Lily's relationship is put on hold as Rufus searches for the child he never knew he had. Meanwhile, Dan does some digging of his own and uncovers Rufus and Lily's secret, putting him in an awkward position.

The students are stressed out as they find out who was accepted and who didn't make the cut for early admission to Yale. Meanwhile, Serena bonds with Rachel, her Shakespeare teacher, who is unaware of what Blair has in store for her following receiving her first B; Chuck finds an unlikely ally in his feud with Jack; and Nate and Vanessa have a romantic evening together.

Blair devises a plan to bring down a teacher; Chuck wakes up in a hotel with little memory of what happened the previous evening.

The Constance Billard and St. Jude seniors have the production of "The Age of Innocence". Serena has a crush on the play's director, Julian, and enlists Vanessa's knowledge of theater to help her get the guy's attention. Blair receives bad news about her future that leads her on a witch hunt for the person responsible. Dan and Rachel agree to stay away from each other in the aftermath of being discovered as more than teacher and student, but find it impossible to keep that promise. Chuck find help on an unlikely friend, Carter Baizen.

Devastated by the turn her life has taken, Blair opts for a wild lifestyle instead of her perfect Waldorf life, causing Chuck and Serena to become concerned. Vanessa tries to convince Nate that he needs to move on after his mother's family, the Vanderbilts, abandoned him and his mother. Trying to be honest with each other, Lily and Rufus both put together their lists of past relationships.

Serena throws Jenny a sixteenth birthday party, but things spin out of control when Poppy Lifton turns the party into the social event of the season. Vanessa agrees to help Chuck in a plan concerning Blair and Nate. Meanwhile, Rufus searches for a way to cover Dan's tuition when he learns he will not receive financial aid to go to Yale.

Serena returns from her trip to Spain with Poppy and Gabriel. Blair makes a secret deal with Nate's grandfather. Dan takes a job to earn money for college.

Georgina returns to the Upper East Side but it's not the same Georgina we all knew, she's changed. Chuck and Nate's relationship is at a crossroads because of their mutual interest in Blair. Serena's relationship with Gabriel gets more complicated.

Blair puts pressure on Georgina to making amends for her past bad behavior by helping her in an evil plan. The rivalry between Nate and Chuck over Blair reaches a boiling point. Lily makes a secret plan to help Rufus with Dan's college tuition.

In a flashback to the 80s, 17-year-old Lily Rhodes (Brittany Snow) gets kicked out of boarding school and runs away to Los Angeles, reconnecting with her parents, Rick (Andrew McCarthy) and Cece (Cynthia Watros), and sister, Carol (Krysten Ritter). Back in present day, Blair and Nate attend prom together, but the evening doesn't turn out exactly as planned and Chuck and Serena have a little something to do with that. Serena and Lily don't see eye-to-eye over Serena's recent run-in with the law. No Doubt performs in the flashbacks as an 80s band called "Snowed Out."

Gossip Girl decides to liven things up at the Constance Billard and St. Jude’s graduation by sending out a shocking and damaging email blast in the midst of the commencement ceremony, stirring Serena to come up with a plan of attack. The Mean Girls (guest stars Yin Chang, Nicole Fiscella, Amanda Setton and Dreama Walker) challenge Jenny to throw her hat in the ring to succeed Blair as Queen Bee next year. Lily and Rufus struggle to repair their relationship after Lily’s betrayal. As for the cliffhangers, Blair and Chuck finally… and Serena is shocked by… and Georgina decides to… and Dan, Nate, and Vanessa unknowingly…. Jenny and Eric do something they might end up regretting...and it all happens in the series’ climatic season finale.