The first comprehensive inside look at the investigation into Al Qaeda, and at John O፥ill, the FBI counter–terrorism agent who warned that an attack like September 11 was imminent. For many people, September 11 was the day ೨e unimaginableߨappened. But one FBI agent, John O፥ill, had repeatedly warned the US Government that such an attack was possible. Ironically, O፥ill lost his own life on September 11, just days after beginning a new job as head of security for the World Trade Center. As one of the FBI's foremost counter–terrorism experts, John O፥ill played a leading role in almost every major investigation of terrorism against Americans in the past decade. O፥ill was a dashing, larger–than–life character who irritated many members of US and foreign governments with his aggressive, hands–on tactics and his insistent, repeated warnings about the possibility of an attack on US soil. Disillusioned by his experiences with the FBI, O፥ill left governmental service to assume the position of chief of security for the Twin Towers in August 2001. Full of twists and turns, John O፥ill's tragic story reveals how one man's unheeded warnings came back to haunt the country he worked so hard to defend.