"Grunhilda the Witch has a weakness - a tiny soft spot on her black and crusty heart. She continues to hide the nice feelings she has when she gets a letter from former Salem Elementary student Madison. But she can't keep up the ruse for long because her familiars are onto her and so are her ancestors! The familiars search her hovel and find her collection of letters from Madison. Mr. Williams has a solution, but it involves making a meanness potion from the book that Is-Not-To-Be-Used-For-Good. But anything that can go wrong does when he accidentally mixes up a positivity potion instead. Birds are singing. Flowers are growing. The principal cancels school! Grunhilda hurries to mix up a potion to fix the town, her familiars, and her own black crusty heart before the positivity succeeds in making everything bright and cheerful"--Publisher annotation.