It's the last story of the season, and Jo is feeling wistful.
Three years of accompanying Doctor Who on his 'never stop drinking' tour-of-the-universe have finally taken their toll, and she's thinking of sneaking off to do something better.
Or maybe she's just thinking, "I need to either get a haircut or bite the bullet and join a Scottish pop-rock group."
This is lovely, isn't it? They still know to have fun, Doctor Who and Jo. It's the first time he seems to have genuinely got on with one of his companions.
Usually when they leave, it's because he's sick of them and kicks them out. Or sometimes they die. A couple of times he seemed to forget they existed, and left the story without them.
I wonder what they're laughing about? All the deaths they've witnessed? And, in some cases, inadvertently caused?
Doctor Who decides to go have his own private adventure in the middle of this story. He goes to a planet made of blue, and steals some of their stuff, including some jewels.
It's never really explained why. I think, by now, he just kind of assumes that everything is his, and that he is the king of everywhere he goes.
Jo, meanwhile, has gone to Wales, to investigate the Green Death, which is what the story is called. She is staying in this house and reading about Green Death, to find out why it happens.
That little guy on the right knows why. It is because he is a giant maggot, and he bites people, and then they catch Green Death. He likes the look of Jo, and he's going to bite her next.
So Jo will soon know the answer, which is good, but she will be too busy going, "Aaarrggg, I've caught Green Death!" to put the information to much use.
It soon becomes apparent that the Green Death is being caused by an Evil Corporation spewing slime into a pit, and making the maggots big and everything.
Doctor Who goes to their building and starts kicking people in the face. He may well have killed the guy on the left. It's a small price to pay, though, for fighting Evil Capitalism.
I like that the guard on the top left is politely waiting his turn to attack Doctor Who. Or maybe he's going to see how the other guard gets on, and then switch allegiance if the answer is 'Doctor Who punches his head off."
Hurray! It's the Brigadier and Sergeant Benton. They've come to Wales too, for their annual adventure running around shooting aliens.
Benton is clearly annoying the Brigadier already. "And do you remember when I shot at the Autons? They died, didn't they? And do you remember when I attacked The Master? He was scared of me, wasn't he? And do you remember when I confronted Omega? He's gone now, isn't he?"
Raaar! The giant maggots are pretty great.
They would make excellent pets. Apart from giving everyone Green Death.
You'd be constantly apologising, and offering to pay for dry cleaning and funeral expenses.
Jo, meanwhile, has decided to spend this adventure finding a boyfriend. Her criteria: "A bit like Doctor Who, but without the drinking, gluttony, inexplicable mood swings and patronising attitude."
She should have also specified something about dress sense and hair. But I guess you can't have everything. This guy is pretty good, and very likeable, and he only occasionally laughs at Jo for being stupid.
The prospect of change has driven Doctor Who to unusual behaviours. Here we see him dressing as a cleaning woman, ostensibly so he can infiltrate the Evil Company.
Then his mate Mike Yates walks in, having infiltrated the company perfectly well while dressed in his normal clothes.
It's fine, Doctor Who. Dress how you want. Your life choices are your own business. You don't need to make excuses to us.
This is the guy in charge of the Evil Company. And that's his Evil Computer, crackling away in the corner.
They're both a lot of fun to spend time with, and say lots of super evil things, like, "Pour more toxic slime into Wales!" and "Cause more Green Death!" and "Eliminate the intruders! Even the ones dressed as women for no reason!"
Doctor Who blows up the computer and gets changed back into what, for him, counts as 'normal clothes'.
He is horrified to discover that, while he's been fighting guys in car parks and shouting at computers, Jo has started having a romance. Weirdly, he seems to be discussing this with guy he's hardly met, rather than asking Jo what's going on.
He's probably saying, "I'd be careful if I were you. She gets captured a lot, and her dress sense is terrible, and she doesn't laugh at really funny jokes until, oh, wait, here comes The Master and apparently suddenly everything he says is the most hilarious thing ever. Also, when you've got a hangover, all she does is laugh and turn up her music."
The boyfriend isn't listening. He's just shouting, "Let's go and make out behind this old guy!"
Jo is off, to live with the other guy. Doctor Who gives her one of the massive diamonds he stole from the blue planet. Jo just accepts this, as if it's a normal gift.
It's a colossal jewel, Jo! He's obviously nicked it! And what are you going to do with it? Put it on a ring?
Actually, look at her rings. That's almost definitely what she's going to do.
Devastated by the loss of his favourite companion yet, Doctor Who turns immediately to alcohol.
He will be sad without Jo, but also he will soon forget what her face looked like and probably her name. And then where he lives.
It's OK. Sergeant Benton or the Brigadier will drive him home. Doctor Who still has people who love him.
He drinks, and he's rude, and he occasionally saves the earth. That's just who he is.