In this sobering and remarkably frank analysis based on her 2011 BBC Radio 4 Reith Lectures, Eliza Manningham-Buller, ex-Director General of MI5, the British security service, talks about key events during her tenure—from 9/11 to the threat of the IRA and al-Qaeda. She states that torture works but must never be used, how intelligence is gathered, why surveillance is necessary to protect democracy, the importance of the rule of law, and why without security there can be no liberty. Eliza Manningham-Buller retired in 2007 after thirty-three years at MI5.