When satellites spot a strange, 2,000-year-old structure in Wales, some suspect a secret connection to King Arthur; using modern-day technology and ancient texts, experts investigate new leads that could point to the mythical Round Table.
| Name | Type | Role | |
|---|---|---|---|
| Keri Leigh Merritt | Guest Star | Self - Historian | |
| Haley Chamberlain | Guest Star | Self - Science Journalist | |
| Rob Nelson | Guest Star | Self - Biologist | |
| Bronwyn Agrios | Guest Star | Self - Image Analyst | |
| Carolyn Finney | Guest Star | Self - Cultural Geographer | |
| Jennifer Lee Jellicorse | Guest Star | Self - History Communicator | |
| Carlo Muñoz | Guest Star | Self - Military Correspondent | |
| Becca Peixotto | Guest Star | Self - Archaeologist | |
| George Kourounis | Guest Star | Self - Explorer | |
| Tracy Fanara | Guest Star | Self - Research Scientist | |
| Guy Walters | Guest Star | Self - Author & Historian | |
| Lindsay Moran | Guest Star | Self - Former CIA Operative | |
| David Krueger | Guest Star | Self - Historian | |
| Randy Cerveny | Guest Star | Self - Climatologist | |
| Sara Carter | Guest Star | Self - Journalist | |
| Patrick Hunt | Guest Star | Self - Archaeologist | |
| Kevin Hymel | Guest Star | Self - Military Historian | |
| Roland Kays | Guest Star | Self - Biologist | |
| Katie Paul | Guest Star | Self - Anthropologist | |
| Eleanor Spicer Rice | Guest Star | Self - Biologist | |
| Adam Ruben | Guest Star | Self - Biologist | |
| Karen Bellinger | Guest Star | Self - Archaeologist | |
| Martin K.A. Morgan | Guest Star | Self - Historian | |
| Trevor Albertson | Guest Star | Self - Former Intelligence Officer | |
| Daniel Sayers | Guest Star | Self - Anthropologist | |
| Mark Horton | Guest Star | Self - Archaeologist |