The notion of a universe inhabited by alien creatures can be found just about everywhere. But could mankind really have been visited by alien beings from other worlds? Experts explore the idea that aliens have been visiting the Earth for centuries.

For decades, the criminal organization known as "The Mafia" has stained the fabric of American society. But what are the secrets behind the Mob's sinister success? Experts uncover the secret world and the violent tactics used to gain money and power.

The Ku Klux Klan members are the original domestic terrorists, hiding underneath white hoods and flowing robes, and taking cover in the rights and freedoms that they are actively seeking to destroy. Experts expose the racist history of the KKK.

Killers are secretly stalking America, hiding in plain sight and compelled by a simple motive to take another person's life. Experts uncover the psychological, biological and sociological make-up of these dangerous murderers.

There are nearly 200 neo-Nazi groups currently operating in the United States -- and they are strongly allied to a loose network of numerous other hate groups. Experts reveal how sympathy for Hitler has grown into a violent subculture of "white power."

According to government statistics, there are an estimated 5,000 cults currently operating in the United States. Experts uncover the psychological allure of cults, their charismatic leaders and the insidious methods for controlling their members.

The office of the President of the United States was designed to operate with greater transparency than any other world-leader... but how much does the public really know about what goes on behind the doors of the Oval Office?

Experts uncover the conspiracies behind America's decades-old drug campaign. They look at why the US government classifies marijuana and heroin as equally dangerous drugs and question whether legal marijuana in some states could change things.

Millions of Americans are obsessed with the mysterious man-ape Bigfoot. Experts shed new light on some of the nation's darkest Sasquatch secrets and reveal new technologies that are being developed for the centuries-old hunt.

Over the last century there have been four successful US Presidential assassinations and a multitude of failed attempts. But do we know the real story behind these assassination plots? Experts look at conspiracy theories surrounding the shocking murders.

No club in America is more secretive than the Hells Angels. Experts and insiders reveal the real story behind the biker brotherhood -- from motorcycle world insiders to club infiltrators to law enforcement officials.