S5, E3: At Diana's (recurring guest star ELIZABETH HURLEY) request, Nate must decide whether to cross moral lines. Dan figures out who is publishing his book and seeks help to stop it, but he still ends up in the spotlight. Chuck helps Dan come to terms with his fate, just as Dan continues to try to help Chuck break through his emotional block. Plus, Serena and Charlie return to the Upper East Side from California, and a Jenny Packham fashion show is featured.