Racial tensions ramp up on the street and at the Knick when a black man stabs a cop; Everett finds a changed operating room on his return to work; and Barrow has concerns about Junia's safety. Meanwhile, Edwards' ingenuity and skills impress Cornelia.moreless
Thackery and Bertie test a new operating-room procedure; Cornelia is second-guessing her impending nuptials; and Thackery considers a salesman's intriguing pitch. Meanwhile, Everett contemplates how to help Eleanor overcome her grief; and Barrow wheels and deals over some used merchandise.moreless
During surgery, Thackery's hand is forced by Algernon, which angers Eleanor; a recovering Abigail regrets her involvement with Thackery; and Sister Harriet and Cleary make a couple of deals. Meanwhile, Bertie receives a scolding from his physician father who is unhappy with his son's career path; and Lucy becomes privy to Thackery's secrets.moreless
As Thackery directs Gallinger and Chickering to conduct experiments on pigs, he ponders whether to operate on a former flame. Barrow goes to great lengths to repay an obligation and get back a missing tooth. Edwards takes out his frustrations at a local bar. Robertson's request for administering treatment to a typhoid fever patient are considered at long last.moreless
Incensed over the problems with the hospital's new electrical system, Thackery instructs hospital superintendent Barrow to get him more cadavers to enable his team to investigate new surgical procedures. As the rate of patient deaths increase, Edwards proffers a technique he learned in France. A typhoid fever epidemic is tackled by Robertson while Thackery confides in Elkins. Edwards figures out another way to carry out his job.moreless
Blair must make the big choice between Dan or Chuck; Lola reflects on Nate asking her to move in with him; Lily makes a final decision regarding her marriage.
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.moreless
Diana and Jack have a deep dark secret; Chuck investigates to find out what is really going on; Dan gets an offer to study abroad in Rome.
Blair and Dan throw out a big party for them to come out as a couple, Gossip Girl may ruin Lola's biggest dream; Serena and Diana have a face-off.
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.moreless
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.moreless
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.moreless
Famed improv troupe, The Upright Citizen's Brigade, selects excerpts from Dan's book to perform. Blair endeavors to save her friendship with Serena by trying to prove her suspicions aren't true.
"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.moreless
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.moreless
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.moreless
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.moreless
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.moreless
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.moreless
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.moreless
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.