Tim Weiner won the Pulitzer Prize for Legacy of Ashes: The History of the CIA. Then, four years after its publication, he received a box of J. Edgar Hoover’s “personal files on [FBI] intelligence operations between 1945 and 1972” from a well-connected D.C. lawyer. That treasure trove of information has since wound up in his recently published book, Enemies: A History of the FBI, and he sat with NPR’s Terry Gross to talk all about it.