At first, this one seems to be falling into the same tired pattern of seven-part stories. UNIT sets up at some new science/power facility, something goes wrong, some creatures appear, the people in charge act foolishly. I can understand why the Doctor is such a grumpy man in this incarnation if this is the sort of thing he has to put up with all the time.
But then the story takes a turn for the interesting. Having removed the console from the Tardis for testing, a surge of power sends it and the Doctor to a parallel dimension, a mirror universe where Britain is a militaristic republic and the power station workers are slave labourers. This immediately reminded me of the episode ‘Mirror, Mirror’ from the original Star Trek series. Although I’m sure it wasn’t the first to pose such a concept, I do wonder if the Doctor Who writers took inspiration from it specifically. I was amused to see Lethbridge-Stewart’s ‘evil’ double sporting an eyepatch and a scar.
Being set in a parallel universe gives the story the freedom to do a genuine disaster without having to worry about the repercussions. In this reality, the drilling facility has achieved faster results, and manages to breach the crust of the planet. Instead of unleashing all new energy sources, it instead unleashes the wrath of the planet, which spews its molten middle everywhere. Inexplicably, green goo from beneath the Earth also turns people into stony-faced hairy zombie cavemen. Yep, I’ve no idea why, but they’re scary-looking things. One criticism, though: the Doctor seems aware of what’s about to happen just before the crust is breached… and yet he’s pretty silent on the issue until then and seems to not care what they’re up to at all.
As the planet literally falls apart around him, the Doctor manages to enlist help and transport his Tardis console back to the correct universe, where he is able to convince them to stop and shut the project down. The company director is such an irritating character, in both universes; I just wanted someone to punch him. Instead, he gradually succumbs to the zombie infection and is incapacitated.
Although longer than it could have been (again), I enjoyed watching this; it was a really good serial and brings season 7 to a satisfying close. But moving on, I do hope there’s a little more variety, and I would like to see the Tardis feature more. Whether the budget didn’t allow the control room to be built, I don’t know, but it’s interesting that the Doctor uses the console on its own and seems intent on leaving without the rest of it!