KATIE CASSIDY AND KEVIN ZEGERS GUEST STAR - Blair (Leighton Meester) and Dan (Penn Badgley) join forces to track down an MIA Juliet (guest star Katie Cassidy). Chuck (Ed Westwick) begins to suspect Lily (Kelly Rutherford) isn't telling him the full truth. Kevin Zegers guest stars as Damien. Blake Lively, Chace Crawford and Matthew Settle also star. Joe Lazarov directed the episode written by Stephanie Savage and Amanda Lasher (#411).