Why is mystery so compelling? The answer goes far beyond detective stories, argues Jonah Lehrer, noting that mystery is the key principle in how humans understand the world—whenever patterns are broken, we are hard-wired to find out why. Exploring how our curiosity has initiated major breakthroughs in medicine and technology, Lehrer also delves into how Harry Potter triggers the magic of dopamine in our brains, why the baseball season is longer than the football season, and when the suspect is introduced in each episode of Law & Order.