The hijackers of September 11 led such outwardly ordinary lives that they moved through Europe and America virtually unnoticed. They plotted in broad daylight, weaving a web of terror from the simple routines of modern life. American flight schools taught them to fly, local banks helped them move money, libraries provided computers, and the Department of Motor Vehicles supplied essential IDs. Everywhere they went they blended in unnoticed and unsuspected. FRONTLINE traces the hijackers' movements across four continents, following clues they left behind to unearth the stories of the individuals inside Osama bin Laden's terror network.