On September 11, 2001, the unimaginable transpired when devastating attacks on the World Trade Center forced the shutdown of the entire U.S. airspace. Thousands of kilometres away in Gander, Newfoundland, a group of Nav Canada air traffic controllers suddenly had the lives of 33,000 people in their hands and had to think fast to find a place for them to go. Discovery uncovers how these unsung heroes managed to safely land 224 planes in four hours, without incident.