On April 30 1980 six heavily armed gunmen burst into the Iranian embassy on Princes Gate overlooking Hyde Park in London. There they took 26 hostages including embassy staff visitors and three British citizens. A tense six-day siege ensued as millions gathered around screens across the country to witness the longest news flash in British television history in which police negotiators and psychiatrists sought a bloodless end to the standoff while the SAS - hitherto an organisation shrouded in secrecy - laid plans for a daring rescue mission: Operation Nimrod. Drawing on unpublished source material exclusive interviews with the SAS and testimony from witnesses including hostages negotiators intelligence officers and the on-site psychiatrist bestselling historian Ben Macintyre takes readers on a gripping journey from the years and weeks of build-up on both sides to the minute-by-minute account of the siege and rescue.