Katie lands the perfect pawn to play on the insecurities of the Westport housewives when she convinces a hot young trophy wife named Harper to volunteer as room mom for Anna-Kat's class, but she quickly shifts gears when Harper rejects Anna-Kat's idea for movie night. Meanwhile, Greg enlists the help of the kids to get Katie's mom, Kathryn, to take an interest in someone other than herself.