Plum discovers that Gavin is the new teaching assistant assigned to her class; Valerie comes to the rescue when an attractive divorced friend tries to seduce Frank; Plum convinces Paulie to sit for the sergeant's exam, despite his lack of confidence; Lydia meets Gavin in the library and, unaware that he's Plum's ex-boyfriend, invites him to be her ""non-date"" for Plum's birthday party.