The Doctor, played by Jon Pertwee, is trying to keep an eye on a group of scientists are dabbling in elements that always lead to some kind of disaster. Yes, they are trying to penetrate the Earth’s crust.

In a secluded location the Government is carrying out secretly drilling operations to tap an ancient power source know as ‘Stahlman’s Gas’. This has been around since the dawn of the universe. At the same time the Doctor is trying to ‘kick start’ his Tardis with the power from the onsite power station.

All is not well, a humble engineer gets exposed to a mysteries green liquid and is transformed into a feral primordial man, that is so hot that everything, bar his clothing seems to be burned.

During one of his experiments with the Tardis he is transport to a parallel earth that is ruled by a powerful dictatorship. In this we see a one eyed Brigadier who is anything but nice and Liz Shaw as authoritarian Section Leader Shaw.

This Earth is suffering the same problems as The Doctor’s Earth in our dimension but they are advanced.

The Doctor struggles to try to save the parallel Earth, but it is too late but not for our Earth.

The Doctor returns to his own dimension and uses the lessons he has learned to save the day.

This episode has the full array of the Jon Pertwee era, Liz Shaw as his assistant, the Brigadier, Sergeant Benton and of course random shooting at creatures and The Doctor!

A brilliant story line that will make old and new fans smile!