Book excerpt: Richard Clarke has been one of America's foremost experts on counterterrorism measures for more than two decades. He has served under four presidents from both parties, beginning in Ronald Reagan's State Department becoming America's first Counter-terrorism Czar under Bill Clinton and remaining for the first two years of George W. Bush's administration. He has seen every piece of intelligence on Al-Qaeda from the beginning; he was in the Situation Room on September 11th and he knows exactly what has taken place under the United State's new Department of Homeland Security. Through gripping, thriller-like scenes, he tells the full story for the first time and explains what the Bush Administration are doing.