In a special edition on the terrorist attacks on America, we hear from the White House official who broke the news to the President and a Muslim first-responder who worked at Ground Zero. Plus, personal memories of the US intelligence failures in the run-up to 9/11 and the bombing of Afghanistan which followed. We also get a dramatic first-hand account of the death of Ahmed Shah Massoud, the leader of the Afghan resistance against the Taleban, who was killed by an al-Qaeda suicide bomber on the eve of the attacks on New York and Washington. And former BBC diplomatic correspondent Jonathan Marcus joins us to analyse the war on terror and the gains made - or not made - in the twenty years since a day which changed the world.

Photo: Smoke pours from the World Trade Centre after it was hit by two passenger planes on September 11, 2001 in New York City. (Credit: Robert Giroux/Getty Images)