Blair (Leighton Meester) is over the moon that she is dating royalty and has every intention of becoming a royal herself, but a scheming Chuck (Ed Westwick) has other plans for Blair and hew new love, Marcus (guest star Patrick Heusinger). Serena (Blake Lively) and Dan (Penn Badgley) agree to keep their recent hook-ups a secret from their friends and family until they figure out what all this means for their relationship. Meanwhile, Nate (Chace Crawford) learns the downside to having an affair with a hot older woman, Catherine (guest star Madchen Amick), who also happens to be married.