Brilliant. Anyone familiar with Jackson's life and fiction knows that she was the perfect candidate to write a book on this subject. This is an outstanding overview of the Salem trials for readers of any age.
I was a little surprised that she brought up the accusation and imprisonment of Dorcas Goode, aged 4, without going on to tell us more about what happened to her. Also, Jackson tells the story of Giles Corey brilliantly, but does leave out the bit about his being asked if he had anything to say as he was being "pressed" to death. "More weight" was his only reply, and it's a memorable one under the circumstances. (Corey refused to enter a plea when accused; he couldn't save his own life, but he was able to ensure that his property was passed down to his sons, rather than forfeited to the state.)
Read this first if you haven't read about the trials; read this *now* if your knowledge of the trials comes primarily from "The Crucible." Not that "The Crucible" isn't brilliant, but it's important to know where Miller shook up the facts.