For centuries, scientists had only one way to study the brain: wait for misfortune to strike - strokes, seizures, infections, lobotomies, horrendous accidents, phantom limbs, Siamese twins - and see how the victims changed afterwards. In many cases their survival was miraculous, and observers marvelled at the transformations that took place when different parts of the brain were destroyed. Parents suddenly couldn't recognise their children. Pillars of the community became pathological liars and paedophiles. Some people couldn't speak but could still sing. Others couldn't read but could write. The stories of these people laid the foundations of modern neuroscience and, century by century, key cases taught scientists what every last region of the brain did. With lucid explanations and incisive wit, Sam Kean explores the brain's secret passageways and recounts the forgotten tales of the ordinary individuals whose struggles, resilience and deep humanity made neuroscience possible.