'This is the story of how your life shapes your brain, and how your brain shapes your life.' Locked in the silence and darkness of your skull, the brain fashions the rich narratives of your reality and your identity. Join renowned neuroscientist David Eagleman for a journey into the questions at the heart of our existence. What is reality? Who are 'you'? How do you make decisions? Why does your brain need other people? How is technology poised to change what it means to be human? In the course of his investigations, Eagleman guides us through the world of extreme sports, criminal justice, facial expressions, genocide, brain surgery, gut feelings, robotics, and the search for immortality. Strap in for a whistle-stop tour into the inner cosmos. In the infinitely dense tangle of billions of brain cells and their trillions of connections, something emerges that you might not have expected to see in there: you.