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.
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 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 hunts for a legendary mass grave that could expose a dark secret from America's industrial past. Then, high in the Blue Ridge Mountains of Virginia, Rob uses cutting-edge technology to find out why a giant lake 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 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 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.