So, fun fact: this serial’s story came from a writer who had been a member of Britain’s Communist Party.
We open our adventure with some Time Lords, concerned the Master is up to no good again, and opting to have the Doctor take care of it. Do they ask the Doctor to take care of it? No. Do they even tell him about it? No.
These guys are jerks.
Anyway, back on Earth, the Doctor is tinkering with his dematerializer, and Jo still doesn’t quite get it that the Doctor can and used to travel across time and space and he’s isn’t just a guy with a weird hobby. The Brigadier pops in with a possible Master update then walks off. The Doctor then opts to let Jo see the inside of the TARDIS…and then the TARDIS shuts the two inside and starts itself, taking the Doctor and Jo off into time and space just as the Brigadier comes back. Where are they going? The Doctor doesn’t know, but he never used to, so why start now?
Eventually, the TARDIS sets down on a planet with a safe atmosphere, so the Doctor and Jo head off to explore. Jo likes some weird flowers, and the Doctor is fascinated by…a rock.
But there’s a colony there, and it’s from Earth, and eventually Jo learns they are 500 years in the future, and the colony there is struggling with crops that aren’t coming in despite all logic, sightings of giant lizards, and a threat from a mining company possibly taking it away from these people who spent their life’s savings to move there. But given these people are worried, they have guards who capture Jo and the Doctor. As it is, the Doctor is soon welcome because he’s really smart and the colony leader Ashe is happy to see someone try to talk everyone out of packing up and going home.
Wait, his name is Ashe?
However, just as the Doctor convinced everyone to stay, a stranger stumbles in, claiming to be the last survivor of a different colony, and then passes out. Now everyone wants to leave again.
Plus, a couple living in an outer dome are killed by something. They did see the giant lizard, and it is a giant lizard. Like, an iguana on a blue screen type. But then the Doctor raises a good point when he comes back to investigate with the less-cool Ashe: a giant lizard couldn’t have fit through the door. Maybe it was the natives? They’re green and carry spears, possibly telepathic since they seem to understand English, but Ashe vouched for them.
No one yet knows those folks stole the TARDIS.
Well, the Doctor does go back to investigate when something does burst through the door. It isn’t a giant lizard or a planetary native.
It’s a mining robot tank with some sharp ends.
I think I know what killed those colonists…