“You’ll never think the same way about your morning cup of coffee.” —Mark McClusky, editor in chief of Wired.com and author of Faster, Higher, Stronger Journalist Murray Carpenter has been under the influence of a drug for nearly three decades. And he’s in good company, because chances are you’re hooked, too. Humans have used caffeine for thousands of years. A bitter white powder in its most essential form, a tablespoon of it would kill even the most habituated user. This addictive, largely unregulated substance is everywhere—in places you’d expect (like coffee and chocolate) and places you wouldn’t (like chewing gum and fruit juice), and Carpenter reveals its impact on soldiers, athletes, and even children.