It's Josh's birthday, so Kate and Owen decide to organise him a fancy-dress party. Josh is not keen, but he relents in the hope that it might give him a chance with Lucy, who lives upstairs and is so nice she would make Mother Teresa look like Katie Hopkins. Meanwhile, Kate meets her ex-boyfriend's new girlfriend Cath, who is obsessed with YouTube videos and will not be deterred by either lack of interest or buffering. And, inevitably, Geoff pops by the party wearing a suitably impractical costume.