While experimenting on an English farthing, Gryffen accidentally creates a sentient currency. Can even the multinational Department defeat 'market forces'?
No, wait, I'm wrong, this is about a robot policeman turned good.
Said robocops - an embarrassing staple of this show since its launch - are usually very stupid, but the Department have been experimenting by augmenting a few of them with human DNA. When one of them gets cut off from the collective, sorry I mean others, our pals are plunged into something very rare indeed for this series - a moral dilemma.
So - should they turn him back into being fully robot and let his human side die? Or encourage his humanity despite his never being able to satisfy it?
The clock is ticking. New department villain Thorne is taking a while to recognise that the regular pattern of events means that whatever evil experiment he's lost will always be found hidden at Gryffen's house. Sure, the penny drops before the end of this episode, but surely he must be starting to spot the tendency by now?
Well, he's not the only one a bit vague on recent events. Despite K9 having guided him around the Department's headquarters with ease last week, this week Starkey is incredulous at the idea.
Starkey: "K9 it's too dangerous. You don't even know your way round."
This local amnesia doesn't go away. When Thorne tries to arrest everyone at the end, he's outwitted by two things:
1. The threat from the alien librarian in the preceding episode on the disc means that he now cannot harm anyone in our gang, so he has to settle for just locking them up for a long time. (as a viewer, it is my responsibility to infer this)
2. This episode is written by someone with a bit of a brain on them. Not only does this result in - shock! - a great deal of discussion, but it also embues Gryffen, Starkey, Jorjie, Darius and K9 with a sudden rush of intelligence. The game of wits that emerges as the two factions gamble not just for their freedom, but also for Birdie the sentient robot's, is sparkling.
Comparisons with the Diet Cybermen and the Borg are inevitable, except that of course no-one in this makes any such comparison. For all Gryffen's knowledge of the history of Centauri, when it comes to basic local history like the battle of nearby Canary Wharf, he apparently knows nothing.
Oh, and Jorjie gets yet another love interest. In a stunning surprise twist, this doesn't last the duration of the episode.
Darn it, I was really rooting for those two.