I slipped sideways.
The Time Lords may have banished the Doctor to Earth, but they didn’t specify which Earth precisely, allowing Don Houghton’s “Inferno” (Story Production Code DDD) to transport our time traveller to a parallel Earth where the biggest difference is that the Brigadier has no mustache. Oh, and in this other dimension England happens to be fascist, too.
The story starts innocently enough, with the Doctor mooching nuclear power from a massive drilling project that aims to tap “Stahlman’s Gas,” a powerful energy source trapped just under Earth’s crust. He’s bent on jump-starting the TARDIS console, which he’s had installed in a pre-fab garage near the drilling site. Apparently he believes that with an independent power source, he can use the console itself to travel through space and time, defeating the Time Lords’ ignition lock. And it works, after a fashion, briefly propelling him, well, somewhere, and allowing Jon Pertwee to ham it up for the cameras again during a scene of dematerialization gone awry.
As for the drilling project, the stage seems set for a standard bureaucratic showdown between an officious administrator and a scientist bent on fulfilling his life’s ambitions, as seen most recently in “Doctor Who and the Silurians.” Almost immediately, the dangers of the drilling project manifest themselves when a rigger is exposed to a green goo leaking from a drill pipe. The viscous viridian substance rapidly de-evolves him into a slavering, primordial being (shades, again, of “Doctor Who and the Silurians,” where encounters with the old lizards trigger a mental retrogression, with hints of the sentient seaweed from “Fury from the Deep” for good measure). Once the lead scientist, Stahlman, accidentally infects himself with the goo, the story seems set on its rails: the goo is dangerous and threatens everyone, so naturally the Doctor will step in and stop the drilling. But after being confronted with evidence of some strangeness afoot, including a a vial of the goo itself and Stahlman’s increasing derangement, the Doctor petulantly focuses his efforts instead on getting more power for his pet project.
And the goo isn’t even the real problem. In a neat bit of subverted expectations, Houghton manages to make green-skinned pseudo-werewolves into mere set dressing, because the planet is about to explode.