A new nuclear facility in the English moors is being plagued with power losses and medical issues with the staff. Is it the stress of the workload or is there something more sinister at work? This week Paddy and Tricia discuss the efforts of The Doctor and Liz as they attempt to locate the source of these issues and see if they have anything to do with the nearby cave system. The fate of humanity could in the balance after a meeting between Doctor Who and the Silurians.