Secrets of the Underground
A search for an underground escape route said to have been used by Al Capone. Also: who or what built earthen mounds in Washington state.
6. California's Hidden Doomsday
0.0Mar 21, 2017 · 60 min
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.