Tunnels filled with human bones lie beneath the streets of Paris, and this horrifying engineering marvel points to a dark secret. New discoveries reveal why this grisly underground death maze was built. Stories: 1) Kienbaum, Berlin, Germany; 2) The Catacombs, Paris, France; 3) Fort Loncin, Liege, Belgium; 4) Cape Romano Dome Home, Florida, USA
| Name | Type | Role | |
|---|---|---|---|
| Tom Williams | Producer | ||
| Luke Wales | Producer | ||
| James S. Corum | Guest Star | Self - Military Historian | |
| Andrew Gough | Guest Star | Self - Historian and Author | |
| Victor Vandarperren | Guest Star | Self - Tour Guide, Fort Loncin | |
| Jim Meigs | Guest Star | Self - Author and Journalist | |
| Dominic Selwood | Guest Star | Self - Historian and Author | |
| Chris Reilly | Guest Star | Self - Boat Captain, Florida | |
| Claire Barratt | Guest Star | Self - Engineer | |
| Rob Bell | Guest Star | Self - Engineer and Adventurer | |
| Sylvie Robin | Guest Star | Self - Archaeologist | |
| Lynette Nusbacher | Guest Star | Self - Military Historian | |
| Dougal Jerram | Guest Star | Self - Earth Scientist | |
| Torsten Gutsche | Guest Star | Self - Former East German Olympic Champion | |
| Neil Laird | Executive Producer | for SCIENCE CHANNEL | |
| Bruce Burgess | Executive Producer | ||
| Henry Scott | Executive Producer | ||
| Tom Williams | Director | ||
| Luke Wales | Director |