We all know where we were that morning. The clear blue sky. The impossible images on our television screens. The moment when time itself seemed to split into before and after.

In this episode of Disturbing History, we go back to September eleventh, two thousand and one, and tell the complete story of the deadliest terrorist attack on American soil. 

From the years of planning in Afghan caves and Hamburg apartments to the final desperate moments aboard four hijacked aircraft, this is the full account of how nineteen men murdered nearly three thousand innocent people and changed the course of history. We trace the origins of al-Qaeda and Osama bin Laden's obsession with striking America. We examine the intelligence failures that allowed the hijackers to train at American flight schools and move freely through the country in the months before the attack. 

We relive the horror of that Tuesday morning as two planes struck the World Trade Center, a third hit the Pentagon, and a fourth was brought down by its own passengers in a Pennsylvania field.

This episode honors the victims, the first responders who climbed toward certain death, and the ordinary people who became heroes when their moment came. We follow the aftermath through the wars in Afghanistan and Iraq, the transformation of American security and society, and the long shadow that September eleventh continues to cast more than two decades later.