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.

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.

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.

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 volunteers to help Dan find a new place to live but their time together brings up unexpected emotions.

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.

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.

Feeling the pressure to make her first Waldorf Designs fashion show a success, Blair must rely on help from an unlikely source, but some unexpected scheming causes a scandal on the runway. Serena discovers that befriending Steven’s daughter Sage is trickier than she thought, especially when she is forced to put her issues with Blair aside to make Sage happy. Nate publishes Dan’s first serialized article causing a stir and producing a serious threat. Meanwhile, Chuck begins to look into the clue that Amira left behind, which may help uncover what Bart is hiding.

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.

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.

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?

Blair enlists Serena to be her stand-in at an important meeting when Blair finds herself needing to be in two places at the same time. Meanwhile, Ivy and Lola team up to help Chuck with a personal vendetta, and Nate makes a decision about the future with Diana Payne.

Chuck, Nate, Blair, Serena and Lola team up to uncover what they think is an explosive secret between Diana and Jack. Meanwhile, Dan is offered a prestigious fellowship in Rome for the summer.

Blair feels like her Upper East Side status might be slipping away and devises a plan to assure that doesn’t happen. Meanwhile, Lily throws a family gathering – including William, Carol and Lola – in an attempt to prove the van der Woodsen family is as united as ever. Finally, Nate digs into Diana’s past and is surprised by what he discovers.

To celebrate their official coming out as a couple, Blair and Dan host a glamorous British-themed Salon, including guests Julian Tepper and Jenna Gribbon Lola lands the audition of a lifetime, but Gossip Girl may have other plans for the Upper East Side’s latest It Girl. Meanwhile, Lily and Rufus disagree over the best way to handle the Ivy situation, and Serena and Diana face-off over secrets they both would prefer remain secrets.

Serena decides she is ready to relinquish the spotlight and sets out to make a reluctant Lola the next “It Girl” of the Upper East Side, starting with modeling at a Kiki de Montparnasse lingerie show. Meanwhile, Chuck reaches out to Blair or advice about his past, and Diana Payne’s return to The Spectator starts a power struggle with Nate.

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.

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.

Dan feels honored when he learns that Upright Citizen’s Brigade is performing excerpts from his book, Inside. Blair tries to prove Serena’s suspicions wrong in order to save their friendship.. On her way out of town, Ivy ends up on a collision course with the van der Woodsens.

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 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.

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 prepares to celebrate her upcoming royal wedding with a bachelorette party, but others scheme behind her back to make this a night to remember. After discovering the truth behind Chuck and Blair’s car accident, Nate joins forces with a surprising ally to gather the evidence. Serena and Dan pretend to be dating again to protect someone close to them.

Blair’s flashbacks reveal the fallout of her and Chuck’s car accident, which Nate realizes may have been caused by foul play. Meanwhile, Lily gets a private eye to locate Charlie; and Vera Wang makes an appearance at Blair’s bridal-dress fitting.

Lily throws Charlie a party to officially introduce her to New York society. Meanwhile, Charlie’s ex-boyfriend, Max, throws a wrench into Charlie’s future as an Upper East Side princess. Dan decides it may be time to tell Blair the truth about his feelings for her.

Lily, Charlie and Serena eagerly anticipate the Studio 54 party being thrown in CeCe’s honor. Nate takes on a new role at the Spectator, but his first big story turns out to be about someone he knows all too well. Blair turns to an unlikely person for help.

Serena is hard at work planning a dream bridal shower for Blair, but it should come as no surprise that Serena has to plant some false information about the shower in order to keep Blair from finding out all the details. Chuck and Dan decide to spend the day together to distract themselves from the fact that they didn’t make the invite list for Blair’s shower. Nate and Serena find a silver bullet in Diana’s war against Gossip Girl, but struggle about whether to use it or not.

Several of our favorite Upper East Siders attend a performance of Punchdrunk’s provocative theater experience, “Sleep No More,” which translates to masks, anonymity and some surprising romantic twists by the end of the evening. Meanwhile, Diana sets her sights on Serena in her quest to ruin Gossip Girl. Dan is out on his book tour, but things aren’t exactly as they appear to his friends and family.

Blair makes all of her former minions and Charlie compete to secure the coveted bridesmaid spots in her upcoming royal wedding. Nate is tired of keeping his relationship with Diana a secret, so he decides to use Charlie to make Diana jealous. Serena’s boss is determined to acquire the film rights to Dan’s book, so Serena must put her personal feelings about Dan and the book aside in order to close the deal.

In the midst of celebrating Yom Kippur with family and friends, Blair and Louis find themselves in a power struggle with Louis’ family. Serena’s boss puts Serena in the awkward position of choosing between her new job and her relationship with Dan. Diana prepares to debut the New York Spectator, but an unfortunate last-minute surprise delays the launch and Diana expects Nate to do whatever it takes to save the day.

After much deliberation, Dan decides to gather Serena, Blair, Nate, Chuck, Rufus and Lily to reveal the truth about his book in the hope that they will support him at his book party. Meanwhile, Blair and Louis hit a crises point after Louis reads Dan’s book. Diana learns incriminating information about one of Nate’s friends and uses it to her advantage.

Nate must decide whether to cross moral lines at Diana’s request. Dan has figured out who is publishing his book, and seeks help to stop it, but he ends up in the spotlight anyway. Chuck helps Dan come to terms with his fate, just as Dan continues to try to help Chuck break through his emotional block. Serena and Charlie return to the Upper East Side from California.

Nate reconnects unexpectedly with Diana, who offers him an exciting opportunity. Serena forces Charlie to decide which world she wants to embrace. Dan seeks out Chuck’s help to stop the publication of his book, but discovers it is Chuck who needs the help. Blair’s future sister-in-law, Beatrice, arrives from Monaco, but her motives with Blair may be more than just to get acquainted.

Serena loves her new job in Hollywood, but makes a costly misstep when she tries to impress her boss. Chuck and Nate arrive in Los Angeles as the last stop of their Lost Summer trip, joining Serena at a glamorous Hollywood Hills party, where Nate meets a sexy older woman. Blair and Louis return from Monaco and begin planning their royal wedding, but when Louis refuses to stand up to his family and support Blair’s choices, his weakness threatens their relationship. A magazine is planning to run an excerpt of Dan’s book until an unlikely ally steps in to help him kill the story.

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.

Charlie is finally starting to feel less like a fish-out-of-water with Serena and her friends, but complications present themselves when Charlie is invited to attend the Constance Billard alumni fundraiser. On the road to “happily ever after” Blair finds herself torn between the men in her life. Jack Bass return to the Upper East Side sets off a chain of events that could end up destroying Chuck and those closest to him.

Blair’s dreams appear to be coming true, but Serena threatens to jeopardize it all by dredging up Blair’s past. Charlie befriends Vanessa, who may or may not have a hidden agenda. Nate is torn between his relationship with Raina and a truth he must keep hidden out of loyalty to Chuck.

Serena enlists Charlie to go undercover Gossip Girl-style to determine why Dan and Blair are spending so much time together, and what role an unexpected visitor is playing in their lives. With Nate’s help, Raina decides to go on a search for her long-lost mother. Chuck’s hopes about his legacy are dashed with the reveal of devastating information from the past.

As Lily awaits the consequences of her decision, William van der Woodsen, CeCe and Lily’s sister, Carol, come into town to support her and be part of a Taschen photo shoot on “modern royalty” in which the Rhodes family is participating. Unbeknownst to Carol, who has always chosen to keep her daughter Charlie far away from the Upper East Side, Charlie has followed her to New York to meet Serena and the rest of the family. Blair has an epiphany about her future, and grapples with the knowledge of whom she’s destined to be with.

Ben’s mother comes to town, forcing issues to the surface between Ben and Serena. Russell Thorpe is determined to destroy Chuck’s family legacy, but he risks alienating his daughter, Raina, in the process. Billy Baldwin returns as William van der Woodsen, Lily’s ex-husband and Serena and Eric’s father.