In 1986, 20-year-old Christopher Knight left his home in Massachusetts, drove to Maine, and disappeared into the woods. Living in a tent in impenetrable forest, he subsisted on food he stole from nearby cabins. He did not have a conversation with another human being for nearly three decades—not until he was arrested for breaking into an empty summer camp for the disabled.

What makes a person abandon the world and become a hermit? Was Chris Knight merely an anti-social loner? Or does he have something important to teach us? These are some of the questions journalist Michael Finkel, who has written for National Geographic, asks in his book The Stranger in the Woods: The Extraordinary Story of