S5, E2: Nate reconnects unexpectedly with Diana (recurring guest star ELIZABETH HURLEY), 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. Meanwhile, Blair's future sister-in-law, Beatrice (recurring guest star ROXANE MESQUIDA – The Last Mistress, Kaboom), arrives from Monaco, but her motives with Blair may be more than just to get acquainted.