Serena's world descends into chaos when a former friend, the evil Georgina Sparks returns to town. Nate connects with the last person he expected, Vanessa. Blair hatches a plan to sabotage her biggest rival, Nelly Yuki. Meanwhile Serena goes out with Georgina, but things get so bad that Serena thinks someone spiked her non-alcoholic drink. Jenny develops a crush on a dog-walker, Asher Hornsby, who might be her ticket to permanent popularity.

Georgina informs Serena that she can reveal a deep dark secret from Serena's past, but no one is prepared for what Georgina does next. Blair and Jenny's power struggle continues when each of them start spreading scandalous rumors about each other on Gossip Girl. Dan sees Jenny's new beau, Asher, cheating on her, but Jenny won't listen to him. Rufus goes to Lily for advice on how to handle Jenny's new behavior. Serena tries to confront Georgina, but she leaves before Serena has a chance. After this, Serena says that she and Georgina are not friends.

After Georgina reveals the true reason Serena left Manhattan, Serena goes back into her old habits. Her friends Blair, Nate, and Chuck, in order to help her, have to put their differences aside. Meanwhile, Rufus is excited when his band is invited to perform at a Rolling Stone-sponsored concert, but Lily is the last person on earth he expects to see at the performance, especially since her wedding rehearsal dinner is the same night.

Blair takes matters into her own hands to help Serena with the manipulative and evil Georgina Sparks. Lily, while keeping Rufus in her mind, prepares for her wedding with Bart Bass that is designed to be the Upper East Side's social event of the year. Serena finally tells Dan the whole truth about her past and they try to work things out after Dan has cheated on her, but will it be too late? An unexpected guest shows up at Lily and Bart's wedding. Georgina is sent somewhere where she can do no harm. Blair plans to go somewhere with Chuck.

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.

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 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.

Blair, determined to have her Queen status at college, starts her first day at NYU along with Dan and Vanessa. However, Georgina, who was assigned as Blair's roommate, sets out to ensure that she does not retain her title. Serena gets ready to move into her dorm at Brown, but has a fight with Chuck before hand. This leads her to search out Chuck's enemy, Carter, to help her get even with him. Meanwhile, Nate and Bree's relationship continues to grow despite the tension their relationship could cause between their families.

Blair and Chuck face-off when the both set their sights on an item up for bid at Sotheby's. Serena begins to think that Carter may have returned to his old habits, Georgina becomes interested in Dan, and Vanessa thinks that something is wrong with Scott.

Lily and Rufus decide to move up their wedding to the next day, but will someone or something come between them before they become man and wife? Chuck discovers a secret that Carter has been keeping from Serena. Dan and Vanessa are pulled into one of Georgina’s schemes. Blair is suspect of Bree and shares her concerns with Nate.

Blair must decide whether to meet Chuck at the top of the Empire State Building or risk losing their future together. A Gossip Girl gossip bomb involving Dan explodes Serena and Nate's relationship. Dorota and Vanya welcome their baby. Jenny hits rock bottom. Georgina returns to the Upper East Side...and she has an agenda.

Blair and Serena spent their summer living it up in the belly of the beast: Paris, France. But where there's Paris there's bound to be boutique, Balenciaga, and of course, boy trouble. Unaware of Chuck's shooting in Prague, Blair struggles to forget him; things take a turn, however, when Chuck mysteriously shows up in Paris with a foreign stunning blonde at his arm. Meanwhile Serena contemplates which of her long-time beaus could be the one for her: Dan or Nate? Even on the Upper East Side drama erupts as Dan figures out the baby mama drama with Georgina, and Nate realizes something about himself when he meets fellow Columbia student, the intriguing Juliet.

On her first day at Columbia, Blair attempts to gain membership into an ultra-exclusive social club, Hamilton House .... but she’s in for a few big surprises. Serena begins to suspect that Juliet is intentionally sabotaging Serena’s life and that it may have something to do with Nate. Rufus is worried about Dan and decides to take matters into his own hands.

The episode continues from the early events of the Constance Alumni event. Georgina Sparks turns up at the event looking for trouble. Serena and Vanessa reluctantly join forces to find Dan and Charlie, who does not take Dan's rejection of her well. Blair must make a choice between the men in her life when her life is in danger by Russell.

The much-anticipated 100th episode will open with a musical dream sequence featuring Serena, Blair and all the men in their lives. Also, while Chuck wrestles with the reality that Blair is about to walk down the aisle with Prince Louis, the return of Georgina Sparks might make the royal affair a royal disaster.

Blair must make a difficult decision about her future, the consequences of which could hurt those she loves most. Serena takes the blame for an incident with Gossip Girl in order to protect someone she loves.. Georgina smells the scent of scandal and decides to follow its trail.

It’s Valentine’s Day on the Upper East Side and Blair can’t resist playing cupid for someone she loves. Georgina is intent on stirring up more drama, so she decides to crash Nate’s Valentine’s Day party. Meanwhile, Serena is shocked by something she witnesses at the party.

Blair thinks Cyrus may have found a potential loophole in her prenup. Chuck and Georgina partner up in a scheme, but it has an unpredictable outcome.. Meanwhile, a family crisis brings William van der Woodsen back to the Upper East Side.

Chuck invites Jack to town to thank him for saving his life, but finds the trip doesn’t go exactly as planned. Blair and Dan attempt to consummate their new relationship -- but unexpected roadblocks get in their way. Meanwhile, Ivy finds an unlikely ally in William in her quest to be accepted on the Upper East Side, and Nate is hopeful a new investor will save his newspaper.

When Gossip Girl goes after Blair as she’s never done before, Serena admits she may have unintentionally played an important role in Blair’s latest nightmare. Meanwhile, Nate invites Lola to move in with him, and Lily must make a big decision about the future of her marriage. Finally, by episode’s end, Blair will make a choice between the two men in her life…will it be Chuck or will it be Dan?

After a brief encounter abroad, Chuck and Blair make a promise to each other about their relationship, which leaves them once again apart. Dan, with some help from an unlikely ally, Georgina, is writing a scathing tell-all book that can only mean trouble. As the sole head of The Spectator, Nate is making his own decisions and is ready to go up against Gossip Girl. As word spreads that Serena is missing, the gang bands together to find her and are shocked by what they find.

Trying to prove herself in adult society, Serena hosts the Central Park Conservancy’s big gala, of which she is now the newest Board Member, and she and Nate both learn something shocking about their significant others. Blair prepares to debut her new fashion line, but a rival from her past holds the key to her future. With the help of Georgina, Dan lands some meetings with publishers, but he must decide if he is willing to sacrifice his integrity in order to get his work published. Meanwhile, Chuck tries to persuade Amira to help him look into his father’s past, even if it means jeopardizing Lily and Bart’s relationship.

Chuck’s continued investigation into his father’s dealings leads him to an unlikely event with Manhattan’s elite, where he hopes to find the one person who can tell him the truth about Bart. Serena and Steven decide to reveal their romantic histories so they aren’t surprised by anything, but neither was prepared for what they uncovered. With The Spectator in jeopardy after Dan decided to publish elsewhere, Nate must make a difficult decision to keep it in business. Meanwhile, Georgina pushes Dan to choose a worthy person to date to boost his image, but he finds himself drawn in a different direction.

After Eleanor gives Blair an ultimatum, Blair is even more determined to remedy Waldorf Designs’ problems by making a splash with a dress at the upcoming Cotillion, but a shocking revelation at the ball affects everyone. Serena becomes worried about Steven’s attitude toward her, but after some investigating she discovers the surprising reason why. Chuck finds an unlikely ally as he tries to drive a wedge between Bart and Lily’s relationship to help expose his father’s secret. Meanwhile, Dan publishes another article, but the effect is just the opposite of what he was hoping for.

Serena and Dan realize that they need to make amends with the people they have wronged. Chuck’s search for evidence of his father’s illegal activities leads him to a showdown with Bart.

Serena and Dan decide to throw their first Thanksgiving together, inviting only their closest friends, but everyone seems to have their own agenda for attending. Feeling defeated by his father, Chuck begins a downward spiral, leaving Blair to find a solution to his problems. Meanwhile, Dan has written his latest exposé, but he must make a tough decision whether to publish it, knowing it could destroy a close friendship.

After a run-in with an increasingly paranoid Bart, Blair grows alarmingly concerned for Chuck’s safety. However, feeling confident that his father will never hurt him, Chuck makes a deal that could change his life. Wanting to make things better for Chuck, Blair devises a plan with the help of Serena, Georgina and Sage to try and get what they need out of Bart. Meanwhile, Nate's financial dilemma finally lands him in a place that he never thought he would be.

In a fashionable farewell to remember, our favorite Upper East Siders join forces for one last soiree, and the shocking identity of Gossip Girl is finally revealed.