Adventure and trouble break out when Mandie returns to The Misses Heathwood's School for Girls in Asheville. The Misses Heathwood are trying to sell their school, but Mandie fears the idea of a new headmistress. If she can only convince Grandmother Taft to buy the school-but where is Grandmother?

School begins and, starting with a sticky mess in the front hallway, Mandie is blamed for a host of things that go wrong. But who's behind all the trouble? April Snow again? And Snowball doesn't help matters. He gets Mandie into even more trouble every time he runs away.

Will Grandmother rescue the school? Can Mandie catch the troublemaker?