Pamela Constable and Arturo Valenzuela. Their new book, "A Nation of Enemies," examines how Chile, , a country with a long history of democracy, slipped into more than a decade of dictatorship under Augusto Pinochet. Constable is Latin America correspondent for the Boston Globe, Valenzuela is director of the Center for Latin American Studies at Georgetown University. (The book's published by W.W. Norton).