This is a good slim volume that gives you a brief history of how the Salem trials have been explained/talked about by historians over the years, starting from accounts by people who lived through them up until the publication of the book in 1979.
It covers pretty much all the major angles; the girls were lying, the girls were driven literally insane by puritanism, the girls were acting as their land hungry parents puppets, the judges were power mad, some of the accused actually were guilty of attempting to curse people, the ergot theory, a more convincing explanation on why ergot doesn't really fit, etc.
It also touches on basic questions like "why is Salem even such a big deal?" "Why was there so much LESS witch hysteria in America than in Europ?"