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.

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 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.

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 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.