September 11, 2001. A disaster so profound that its name is derived not from the horrifying events that took place that day, but by the date alone—as though what happened was so unspeakable that the only way to properly encompass the enormity of it is to invoke when it happened; a date that, to paraphrase Franklin Roosevelt's description of Pearl Harbor Day, truly lives in infamy. When Al-Qaeda operatives struck at the heart of America's financial and military might—the World Trade Center (WTC) in New York City and the Pentagon just outside of Washington, DC—killing more than 3,000 Americans, our country was changed forever. In the aftermath came two wars and passage of the Patriot Act, which redefined how the U.S. could spy on its own citizens.

But after nine years, most Americans have as many questions about the details and aftermath of the savage attacks as they do about the motives of the monsters behind it. Why did some at Ground Zero claim to hear explosions before the first plane even hit? How could two planes crash in a major metropolis and not a single flight data recorder be found? Why did WTC Tower Seven collapse when it was not hit by either of the two airliners? And why won't the government admit that some tests have found traces of explosives in the wreckage from the towers?

While some are merely puzzled, or unworried about these questions, others track down answers like bloodhounds, subjecting themselves to the scorn and ridicule of many who feel that these questions shouldn't be asked. Commissions have been formed, reports issued and books written, but these questions and others like them remain unanswered by the federal government, leading to much speculation that perhaps the U.S. government had advance knowledge of—or even helped plan—the attacks.