Book excerpt: The 9/11 attacks on America marked the beginning of a new era in history, one in which everyday safety is no longer taken for granted. But the forces that triggered those horrific actions have been in place for years -- and experts estimate that as many as 500 terrorist cells exist in America today. In The Cell, John Miller and Michael Stone follow the key agents and detectives who know their whereabouts. Listeners will join in the step-by-step process of identifying and linking suspects, as well as learn the politics and pressures, the magnitude and the feel of the greatest manhunt in the history of the world.