Blair is over the moon that she is dating royalty and has every intention of becoming a royal herself, but a scheming Chuck has other plans for Blair and hew new love, Marcus. Serena and Dan 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 learns the downside to having an affair with a hot older woman, Catherine, who also happens to be married.