FROM THE MOMENT the first airplane crashed into the World Trade Center on the morning of September 11, 2001, the world has asked one simple and compelling question: How could it happen? Three and a half years later, not everyone is convinced we know the truth. Go to Google.com, type in the search phrase "World Trade Center conspiracy" and you'll get links to an estimated 628,000 Web sites. More than 3000 books on 9/11 have been published; many of them reject the official consensus that hijackers associated with Osama bin Laden and Al Qaeda flew passenger planes into U.S. landmarks.
