Near the destroyed city of Pompeii, an eerie complex of underground tunnels snake beneath a volcano, and some believe these passages were intended as a gateway to hell. Stories: 1) Berlin-Hohenschönhausen, former East Germany; 2) Drydock No. 1, California, USA; 3) Baia Archaeological Park, Naples, Italy; 4) Isla San Lucas, Costa Rica
| Name | Type | Role | |
|---|---|---|---|
| Tom Williams | Producer | ||
| Luke Wales | Producer | ||
| Rob Bell | Guest Star | Self - Engineer and Adventurer | |
| Sascha Auerbach | Guest Star | Self - Historian | |
| Jim Meigs | Guest Star | Self - Author and Journalist | |
| Graziano Ferrari | Guest Star | Self - Speleologist | |
| Andrew Gough | Guest Star | Self - Historian and Author | |
| Bruce Christensen | Guest Star | Self - Engineer | |
| Claire Barratt | Guest Star | Self - Engineer | |
| Peter Keup | Guest Star | Self - Former Inmate, Hohenschonhausen | |
| Dougal Jerram | Guest Star | Self - Earth Scientist | |
| Shini Somara | Guest Star | Self - Engineer | |
| James S. Corum | Guest Star | Self - Military Historian | |
| Fran Scott | Guest Star | Self - Scientist | |
| Eloy Mora Solorozano | Guest Star | Self - Former Inmate, Isla San Lucas Prison | |
| Lynette Nusbacher | Guest Star | Self - Military Historian | |
| Bruce Burgess | Executive Producer | ||
| Henry Scott | Executive Producer | ||
| Neil Laird | Executive Producer | for SCIENCE CHANNEL | |
| Tom Williams | Director | ||
| Luke Wales | Director |