Ten years after 9/11, this fascinating investigation revisits the morning's events. The odd absolute certainty and a handful of urban legends sustained by distorted truths and bloody mindedness. What do we really know about the pilots? Who exactly were they? Whose orders were they acting under? Could they have been stopped? How did the situation escalate to the point it did?

The second chapter in this investigation into the factors that led to the 9/11 attacks, with a reconstruction of the pursuit of Al Qaeda between 1993 and 2001. This episode pieces together the puzzle of the pursuit of Al Qaeda, highlighting the missed opportunities that spiralled inexorably into the events of the morning of 11 September 2001.