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.

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.