Miss Nelson's is the worst class in the entire school and she can't control them because she's just too nice. But when she disappears, her replacement is the hard-as-nails, detention-loving, recess-canceling, homework-overloading substitute teacher Viola Swamp! With the Big Test approaching, the kids suddenly realize how much they miss Miss Nelson and they'll do anything -- including hiring a private eye -- to solve the mystery of her disappearance and bring her back.