Spoiler Alert!

Spoilers get folks upset—really upset. One thing that follows from this is that if you pick up a book that’s all about spoilers, it may seriously disturb you. So anyone reading this book—or even dipping into it—does so at their peril.

Spoilers have a long history, going back to the time when some Greek theater-goer shouted “That’s Oedipus’s mom!” But spoilers didn’t use to be so intensely despised...