On the day of the US attacks hundreds of hours of military and air traffic control conversations were captured on tape.
With the help of these recordings this film shows how fighter jets that were scrambled to protect Washington set off in the wrong direction and ended up over the Atlantic.
It also shows how the go-ahead to fire on the hijacked planes came through only after the last one had crashed and how fighter jets were still 100 miles away when the second plane crashed into the Twin Towers.
With testimonies from the people who appear on the tapes, the film vividly conveys the emotion, courage and panic in the voices of all concerned.