On September 11, 2001, filmmaker James Hanlon and Jules and Gedeon Naudet were filming a documentary on a rookie New York City firefighter when they noticed a plane overhead. That plane would hit the World Trade Center. They rushed immediately to the scene. James Hanlon and the Naudets filmed throughout Sept. 11 and the days afterward from the firemen's perspective, as it became clear to them that this was the only known footage from inside the Twin Towers that day.