The escalating danger in Llanfairfach Colliery requiring immediate intervention to prevent disaster

A scientist desperate to escape the collapsing tunnels of the abandoned Llanfairfach colliery stumbles through the darkened, unstable passageways. The colliery’s official closure signs belie the dangerous activity below where …

The Doctor and Brigadier Lethbridge-Stewart arrive at Llanfairfach Colliery just as Jo Grant and Bert begin descending into the unstable mine shaft where a covert environmental experiment has taken hold. …