A Centenary History of MI5

What revelations are contained in the files of MI5, the deeply mysterious security and intelligence agency that has protected Great Britain for the past 100 years? We’ll talk to Britain’s leading historian of intelligence, Christopher Andrew, a professor of Modern and Contemporary History at Cambridge University and author of the new book, “Defend the Realm: A Centenary History of MI5” (Alfred A. Knopf, 2009).