The Eternal Fire

S1, E3: The team explores a mystery close to home as a cave linked to Warrior Queen Boudica is discovered near their UK base and Gillian and Ben find themselves in a race against time to escape dangerous gases when they're trapped underground. When a dig at the famous Roman Baths unearths a beautiful and ornate cave, it soon becomes clear that it was used to hold two prisoners. Team leader Gillian is convinced that Boudica wasn't killed in battle as believed, but was actually held captive for many years – could this be the place where she was hidden away? But who was the other one and what was their connection to the Warrior Queen? Unbeknown to the rest of the team, Gillian and Ben go back inside but are trapped as a tunnel collapses, and have to dodge centuries-old booby traps and toxic gases in their desperate bid to escape.