We speak with S.C. Gwynne, author of "Empire of the Summer Moon: Quanah Parker and the Rise and Fall of the Comanches, the Most Powerful Indian Tribe in American History." The book explores the sprawling story of the Comanches, their rise to greatness in the American West, and what ultimately led to their demise. The book also explores the life of the last great Comanche war chief, Quanah Parker, who had an amazingly acute perception of and appreciation for western practices and attitudes.