On That DayAnyone who experienced the attacks on September 11 cannot forget the imagery: the smoking, falling towers, the Pentagon smouldering, the Shanksville crash site, the first responders. But there is an invisible story hidden in the wreckage, one that required years of patient investigation and the piecing together of a sequence from many scattered sources. By establishing the most definitive timeline of how that day unfolded, William M. Arkin shows how