Serena (Blake Lively) loves her new job in Hollywood, but makes a costly misstep when she tries to impress her boss (guest star Michael Michele). Chuck (Ed Westwick) and Nate (Chace Crawford) arrive in Los Angeles as the last stop of their Lost Summer trip, joining Serena at a glamorous Hollywood Hills party, where Nate meets a sexy older woman (guest star Elizabeth Hurley).
Blair (Leighton Meester) and Louis (guest star Hugo Becker) return from Monaco and begin planning their royal wedding, but when Louis refuses to stand up to his family and support Blair's choices, his weakness threatens their relationship. A magazine is planning to run an excerpt of Dan's book until an unlikely ally steps in to help him kill the story. Kaylee DeFer and Matthew Settle also star.
Gossip Girl airs every Thursday at 8 p.m. on ETC.