Episode 1
Rob Nelson investigates rumors of a secret underground escape route used by the infamous gangster Al Capone. In Washington state, Rob tries to uncover who -- or what -- built a vast landscape of earthen mounds in Washington state.
Episode 2
Rob Nelson explores mysterious tunnels beneath Denver's airport and capitol building to investigate rumors of a secret organization operating below. In Ohio, he tries to uncover the ancient secrets of a mound shaped like a serpent.
Episode 3
Rob Nelson hunts for a legendary mass grave that could expose a dark secret of America's industrial past. High in the mountains, a giant lake is mysteriously disappearing, and Rob uses cutting-edge technology to find out why.
Episode 4
Rob Nelson examines a set of bizarre markings that suggest a violent clash between prehistoric beasts. In California, he investigates if a strange lake is a home to alien life.
Episode 5
Rob descends into a cave 30 feet beneath Texas in search of evidence of a mass extinction event. Then, he heads to Lake Michigan to investigate a Bermuda Triangle-like phenomenon that has caused ships to vanish for centuries.
Episode 6
Rob Nelson heads to California to investigate a network for major fault lines that could set off an unprecedented mega-quake. Then, he explores a mysterious sinkhole that some believe is an endless pit to the center of the Earth.
Episode 7
Rob investigates ancient ruins in New England that suggest Europeans arrived in the Americas almost 1,000 years before Columbus. Then, he heads to California where a dormant super-volcano may be showing new signs of life.
Episode 8
Rob Nelson investigates the mysterious pattern of rocks at the bottom of Lake Michigan known as Underwater Stonehenge. At the notorious Alcatraz prison, Rob uses state-of-the-art technology in search of rumored escape tunnels.
