It is September 11th, 2001, and shortly after taking off from Washington DC, hijackers storm the cockpit of American Airlines Flight 77 and fly the plane into the Pentagon. The symbol of US military might is in flames.

After a one-hour flight from Taiwan, China Airlines Flight 120 touches down in Okinawa, Japan. The pilots park the Boeing 737 and switch off the engines. But just as they complete the shutdown checklist, a fire erupts and the aircraft is engulfed in flames. Incredibly, everyone on board escapes the inferno without injury. But the disaster leaves an international team of investigators with troubling questions. The hunt for answers seems like an endless quest as the smallest components come under intense scrutiny. The analysis eventually leads to a stunning discovery-the tiny failure that doomed Flight 120 is endangering lives around the world.