When Blair's father, Harold, comes home for the holidays with an unexpected guest -- his boyfriend, Roman -- Blair finds it difficult to hide her disappointment and hatches a plan to get rid of Roman for good. Jenny and Vanessa help Serena plan the best Christmas surprise ever for Dan, who may have a surprise of his own in mind for Serena. Chuck texts Blair that Nate has joined him in Monaco, worrying Blair that Chuck may disclose the details of their hook-up. Rufus refuses to remain the understanding husband any longer after Alison's former lover calls the house.
The title of this episode comes from the 1953 film "Roman Holiday".