‘Welcome to the underworld.’ It’s a thankless task having to follow Robert Holmes with another script about a downtrodden slave class rising up against their masters. The difference with The Sun Makers is that we’ve been led to care about Cordo, whereas the ‘Trogs’ here are introduced in a scene that’s worse than the villagers in Planet of the Spiders, as the rebel leader implores, with no conviction, ‘May the sky fall on your families.’ Plus we also meet a lot of guards who dress like Darth Vader if they’d kept Dave Prowse’s voice, waffling on about sacrifices to the Oracle. It’s a lot to take in when we’ve barely got to know the R1C crew (who sort of fade into the background now), and the result is an episode that doesn’t seem to have much of a through line, just a bunch of stuff that’s thrown at us.

It doesn’t help that this is the episode where the money runs out. The actual sets don’t look bad – they’re a bit sparse and grim, but that works for the story. But the CSO caves look more like waxy earholes, giving me flashbacks to The Invisible Enemy, and I suspect the limitations and frustrations of having to work without proper staging robs this of some of its pace, and makes a lot of it feel a bit under-rehearsed and choppy. The Doctor and Idas sound like two actors saying their lines, rather than two characters meeting for the first time and striking up a bond.

Given the production nightmares and the effort that must have gone in to making this at all, it’s sad that the end product is so half bothered. K9 doesn’t even get proper electric cable clamps on his ears – someone’s just found a couple of bulldog clips from the stationery cupboard. The Doctor says, ‘Whatever blows can be sucked’ and this certainly both sucks and blows.

Next episode: Underworld – Part Three