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.

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.

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.