Penn Badgley

Serena must be Blair's double when Blair finds herself needed in multiple places at once; Chuck enlists the help of both Ivy & Lola in order to carry out a revenge plot; Nate sorts out his future with Diana Payne.

Serena is determined to turn Lola into the next "it-girl" of the Upper West Side, starting with trying to persuade Lola to model at a Kiki de Montparnasse Lingerie show. Meanwhile, Chuck reached out to Blair for advice about his past. Diana Payne's return to The Spectator starts a power struggle with Nat for control, while Lola reacts with jealousy; but everything is not what it appears. It is discovered that Chuck paid Blair's dowry to get rid of Louis' family. Also, Rufus and Lily have a falling out after Lily goes behind Rufus' back to play a simply scheme to remove Ivy from their penthouse.

Chuck thanks his uncle Jack for saving his life. Blair and Dan try to take their relationship to the next level. Lily has tries to adapt to living in Brooklyn while Ivy adapts to her new life on the Upper East Side. Serena takes on the role as Gossip Girl from the package Georgina left her.

William van der Woodsen returns to the Upper East Side to deal with a family emergency, while Blair fears Cyrus has found a loophole somewhere in her prenup. Also, Georginia and Chuck band together with a mischievous plot, leading to an unpredictable finish.

As Valentines Day is in full swing on the Upper East Side, Blair takes it upon herself to play Cupid. Among all the loving feelings Georgina decides to cause trouble, by gate-crashing Nate's Valentine's party. The drama of the party continues as an event that secretly unfolds there shocks Serena.

"The Backup Dan" begins with Blair and Dan successfully fleeing all the way to the airport to make their escape from New York. Elsewhere on the Upper East Side, Georgia has discovered some scandalous gossip and her newly revealed nature means she will not be letting it get away from her.

As Blair prepares to walk down the aisle, Chuck tries to come to grips with losing the love of his life. Michelle Trachtenberg returns as Georgina to cause trouble, plus other surprises in the 100th episode.

It's Blair's bachelorette party, but others scheme behind her back to ruin the night. After discovering the truth behind Chuck and Blair's car accident, Nate and a surprising ally, gather the evidence. Meanwhile Serena and Dan pretend to be together again to protect someone close to them.

Blair confides in Serena about what happened after her car accident with Chuck. Meanwhile, Nate investigates possible foul-play causing the accident. Lily hires a private detective to track down Charlie. And Blair gets a wedding-dress fitting by Vera Wang herself!

While Lily throws a coming out to society party for Charlie, Serena and Dan try to amend their friendship. It is now time for Blair to choose between Louis and Chuck, she receives help from Dan who has an agenda of his own. Max still tries to leak Charlie's story and at the end of the night she slips Gossip Girl information that could turn deadly.

Lily, Charlie and Serena anticipate a party thrown in CeCe's honor. Nate takes on a new role at the Spectator, and his first big job is of someone he knows very well. Meanwhile, Blair turns to an unlikely source for help.

Serena plans a dream bridal shower for Blair, but she has to plant false information about the event so that Blair does not find out. Chuck and Dan spend the day together to forget that they were not invited to Blair's shower. Nate and Serena find something about Diana and struggle with how and when to use it.

The gang attend a performance of Punchdrunk's provocative theater experience, "Sleep No More," which translates into masks, anonymity and some surprising romantic twists by the end of the evening. Meanwhile, Diana's target is Serena in her quest to ruin Gossip Girl. Dan is out on his book tour, but things are not as they appear to be to his friends and family.

Blair makes a competition to fill her bridesmaids spots in her upcoming royal wedding. Meanwhile Nate is tired of keeping the secret of his relationship to Diana, so he decides to use Charlie to make Diana jealous. Serena's boss wants to acquire the film rights to Dan's book, so Serena has to put her personal feelings aside to close the deal.

In the celebration of Yom Kippur with family and friends, Blair and Louis have a power struggle with Louis's family. Serena's boss asks her to choose between her new job and Dan. Diana prepares to debut the New York Spectator, but a surprise delays the launch and Diana expects Nate to help her.

After much thought, Dan finally decides to gather everyone and reveal the truth about his book, hoping that they will support him at his book party. Meanwhile, Blair and Louis struggle after Louis reads Dan's book. Diana has some incriminating information about one of Nate's friends and uses it to her advantage.

Nate has to decide whether to cross moral lines at Diana's request. Dan is trying to figure out who is publishing his book, and seeks help to stop it but ends up in the spotlight anyway. Chuck helps Dan and Dan helps Chuck break through. Meanwhile, Serena and Charlie return to the Upper East Side.

Nate reconnects with Diana, who offers him an exciting opportunity. Serena forces Charlie to make a choice between worlds. Dan seeks out Chuck's help to stop the publication of his book, but discovers that Chuck is the one who needs help. Blair's future sister-in-law, Beatrice, arrives from Monaco, but her motives with Blair may be more than just to getacquainted.

Serena loves her new job in Hollywood, but makes a mistake trying to impress her boss. Chuck and Nate arrive in LA as their last stop of their Lost Summer trip, joining Serena at a glamorous party, where Nate meets a sexy older woman. Blair and Louis return from Monaco and begin planning their royal wedding, but when Louis refuse to support Blair's decisions against his family, their relation is at risk. A magazine is planning to run an excerpt of Dan's book until an unlikely ally helps him.

In the season four finale, will Blair choose her prince or her dark night?
The finale includes the return of Georgina and Constance Billard mean girls Kati and Is, a cameo by "Gossip Girl" author Cecily von Ziegesar, a performance by Airborne Toxic Event and, oh yeah, a few very juicy cliffhangers.