9/11: Truth, Lies and Conspiracies.

Half of Americans believe they haven't been told the whole story about 9/11. We've all heard the conspiracy theories, but why do they continue to grip some people so tightly? In this thought-provoking exploration of one of America's greatest tragedies, victims' families, a senior politician, and intelligence agency insiders discuss their belief that there's much more to this story than we know.