September 11, 2001 marked the beginning of a new era in history, but the forces that triggered those attacks have been in place for years and continue to operate within the United States and abroad. Experts estimate that as many as 500 terrorist cells exist in America today. ABC News journalist John Miller has been tracking this story since his coverage of the first World Trade Center bombing in 1993. He was the first American journalist to interview Osama Bin Laden, and he has a sophisticated knowledge of the structure and workings of extremist organizations. The Cell contains information gleaned from sources within the FBI, CIA, and the local law enforcement communities currently conducting the investigation into the September 11 attacks.