Secrets of the Underground

Rob Nelson investigates rumors of a secret, underground escape route used by the infamous gangster Al Capone in Louisville, KY. Also, the Mima mounds in Washington State are explored.

Rob Nelson explores mysterious tunnels beneath Denver's airport, capitol building, and downtown to investigate rumors of a secret organization. Also, the ancient secrets of a giant mound shaped like a serpent are investigated.

Rob Nelson hunts for a legendary mass grave that could expose a dark secret from America's industrial past. Also, cutting edge technology is used to find out why a giant lake in Virginia suddenly vanished.

Rob Nelson examines a set of bizarre markings on a Colorado ridge that suggest a violent clash between prehistoric beasts. Also, an ancient California lake is investigated to see if it's home to alien life.

Rob Nelson descends into a Texas cave to uncover ancient remains of an unknown, mass extinction. Also, a phenomenon that's caused ships to disappear for centuries in the placid waters of Lake Michigan is investigated.

Rob Nelson heads to California to investigate a network of major fault lines that could set off a massive earthquake. Also, a mysterious sinkhole is explored that some believe is a portal to the center of the Earth.

Rob Nelson investigates a cluster of ancient ruins that suggest Europeans arrived in North America almost 1,000 years before Columbus. Also, a dormant supervolcano may be showing new signs of life.

Rob Nelson uses state-of-the-art technology to search for rumored escape tunnels deep beneath Alcatraz. Also, a mysterious pattern of rocks is investigated at the bottom of Lake Michigan.