New book on Northern Ireland chronicles fallout from peace

The book, "Say Nothing: A True Story of Murder and Memory in Northern Ireland," starts with the 1972 killing of Jean McConville, a widowed Belfast mother and one of roughly 3,500 people who died in brutal decades-long sectarian conflict over Northern Ireland. Author Patrick Radden Keefe sits down with William Brangham to discuss the "intense" experience of writing the book.