Episodio Dieciocho Much 'I do' about nothing

With her best friend Serena's (Blake Lively) life and reputation on the line, Blair (Leighton Meester) decides to take matters into her own hands in dealing with the manipulative and evil Georgina Sparks (guest star Michelle Trachtenberg). With Rufus (Matthew Settle) never far from her thoughts, Lily (Kelly Rutherford) prepares for her wedding day which is destined to be the Upper East Side's social event of the year. Serena finally pours out her heart and the truth about her past to Dan (Penn Badgley), but will it prove to be too late to save their relationship?

Heiress and model Lydia Hearst guest stars in the episode as Amelia, Lily's interior decorator.