A Nazi fortress that could have changed history if it was finished, an underwater graveyard of unexpected American treasures, and a network of tunnels hiding a secret history of New York. Stories: 1) La Coupole, Pas De Calais, France; 2) Red Army HQ, Wünsdorf, Germany; 3) SS Empire Heritage, Malin Head, Ireland; 4) Old Croton Aqueduct, New York State, USA
| Name | Type | Role | |
|---|---|---|---|
| Luke Wales | Producer | ||
| Amena Hasan | Producer | ||
| Jane Cameron | Producer | Series Producer | |
| Katherine 'Kate' Swanson | Producer | ||
| Dougal Jerram | Guest Star | Self - Earth Scientist | |
| Dominic Selwood | Guest Star | Self - Historian and Author | |
| James S. Corum | Guest Star | Self - Military Historian | |
| Mavis Cain | Guest Star | Self - Friends of Old Croton | |
| Jim Meigs | Guest Star | Self - Author and Journalist | |
| Rob Bell | Guest Star | Self - Engineer and Adventurer | |
| Jürgen Naumann | Guest Star | Self - Caretaker, Wünsdorf Soviet Army Headquarters | |
| Andrew Gough | Guest Star | Self - Historian and Author | |
| Geoff Millar | Guest Star | Self - Dive North | |
| Laurent Thierry | Guest Star | Self - Historian | |
| Roma Agrawal | Guest Star | Self - Structural Engineer | |
| Lynette Nusbacher | Guest Star | Self - Military Historian | |
| Henry Scott | Executive Producer | ||
| Neil Laird | Executive Producer | for SCIENCE CHANNEL | |
| Bruce Burgess | Executive Producer | ||
| Katherine 'Kate' Swanson | Director | ||
| Luke Wales | Director |