Author David Grann often writes about obsession. His stories feature people doing extraordinary, and often dangerous or morally questionable, things in pursuit of ambitious goals. He’s the author of the books “Lost City of Z,” “Killers of the Flower Moon,” and “The Wager.” Grann is also obsessive himself - about the research and details he puts into his books. We talk to Grann in front of a group of students at Nelson High School in Happy Valley.