Parys Mountain on Anglesey is riddled with old copper workings, some dug in the Bronze Age and others abandoned more recently, and this Channel 4 production follows archaeologist Dr Mark Davies as his team descends into the unstable tunnels to hunt for artefacts left by the earliest miners. The goal is a specific one: to force a physical breakthrough connecting the Parys workings to the neighboring Mona mine, a passage that has been sealed for years. Dr Alice Roberts appears as part of the team, in an early television role before she became a familiar presenter, distinctive here with pink hair. The film spends its time underground rather than in a studio, with the crew navigating flooded shafts and crumbling rock faces while trying to date the tool marks and debris they find against the site's Bronze Age copper-mining history. It is a hands-on dig rather than a survey of theories, built around getting people and cameras into places archaeologists do not usually go.