Now on Best Kept Secrets: a glimpse inside America's most dangerous and mysterious secret societies. What secrets are locked inside the Tomb of Skull and Bones? And who belongs to this prestigious and private fraternity? Answer: some of the most powerful people on the planet. Next, Earth First. They call themselves peaceful environmentalists. But are they putting innocent lives in danger? Plus the Secrets of the Ku Klux Klan revealed. From the Klan's secret handshake, to the hidden meaning of the KKK symbol. We take you inside the most feared secret society in America. Next, this mild-mannered professor is the voice of The National Alliance, but is he also the inspiration behind the Oklahoma City bombing? Last, what's in a rave? Youth, music, all-night parties and drug abuse? These stories and more on Best Kept Secrets.