Host Don Wildman explores underground Los Angeles, including a haven for killer Charles Manson and his followers, tunnels where corrupt cops secretly ran the city, a dormant subway system, coastal military bunkers, and city war rooms ready for the next big quake.

Christianity evolves in unique ways in Ethiopia's ancient underground engineering marvels and remote, cliffhanging caves; emperors tombs; subterranean cathedrals; the Queen of Sheba's buried palace; possible site of the Ark of the Covenant.