A Mediterranean island paradise is not all that it seems; its complex of abandoned buildings were once prisons for the world's most dangerous Mafiosi; experts investigate new evidence to reveal who was imprisoned here and the secrets they left behind. Stories: 1) Fort Saint Elmo, Valletta, Malta; 2) Dredge Number 5, Nome, Alaska; 3) Alddreu Airfield, Jeju Island, South Korea; 4) Asinara Island, Sardinia, Italy
| Name | Type | Role | |
|---|---|---|---|
| Tom Williams | Producer | Series Producer | |
| Andrew Lessner | Producer | for SCIENCE CHANNEL | |
| Luke Wales | Producer | Series Producer | |
| Jim Meigs | Guest Star | Self - Author and Journalist | |
| Enrico Mereu | Guest Star | Self - Former Prison Guard, Asinara Island, Sardinia, Italy | |
| Lynette Nusbacher | Guest Star | Self - Military Historian | |
| Claire Barratt | Guest Star | Self - Engineer | |
| Sascha Auerbach | Guest Star | Self - Historian | |
| Ryan Vella | Guest Star | Self - Local Historian, Malta | |
| Geoffrey 'Geoff' Wawro | Guest Star | Self - Historian and Author | |
| Rob Bell | Guest Star | Self - Engineer and Adventurer | |
| Michele Mitchell | Guest Star | Self - Historian and Author | |
| Lee Yun-Heong | Guest Star | Self - Journalist | |
| Charles Debono | Guest Star | Self - Resident Historian, Malta | |
| Bob Hafner | Guest Star | Self - Nome Resident, Alaska | |
| Gianmaria Deriv | Guest Star | Self - Former Prison Guard, Asinara Island, Sardinia, Italy | |
| Dougal Jerram | Guest Star | Self - Earth Scientist | |
| Bruce Burgess | Executive Producer | ||
| Henry Scott | Executive Producer | ||
| Neil Laird | Executive Producer | for SCIENCE CHANNEL | |
| Tom Williams | Director | ||
| Luke Wales | Director |