Like Planet of Evil, after a promising first half this starts to go to pieces in Part Three. Part of the problem is that Terry Nation seems to have lost interest, so instead of the kind of ethical debates and mounting dread in the latter half of Genesis of the Daleks this becomes a roll-call of Nation clichés: a radioactive planet; a deadly virus that will wipe out life; android doubles. And whereas Robert Holmes presumably did a lot of work on Genesis, in Season 13 he’s got his hands fully rewriting Pyramids of Mars and The Brain of Morbius. The result is an incredibly slapdash episode.

That’s reflected in the fact that Styggron has an over-elaborate plan that he’s executing in an incredibly offhand way. Sarah Jane, who’s meant to be under close guard just seems to wander out of the Kraal base in time to rescue the Doctor and then race back to get captured. The deadly plague that’s meant to eradicate mankind doesn’t seem to have been properly tested, and Styggron’s live test, on Sarah, is conducted without him even checking whether she drinks the poisoned water (she doesn’t). Crayford’s backstory is info-dumped massively, and some of it is memorably horrid (he had to conduct euphemistic ‘recycling experiments’ to conserve his capsule’s water, and the Kraals reconstructed him with the grisly omission of ‘one eye that couldn’t be found’), but the fact the episode just stops for him to explain all is a dull contrast to the graceful exposition of Pyramids of Mars.

It’s not like these kind of plot weaknesses don’t occasionally crop up in a lot of Doctor Who, but there are an egregious number here. It’s hard to imagine Terrance Dicks allowing quite so many contrivances and half-bothered moments to creep through. I think this probably reflects a wider truth about Robert Holmes: when he’s interested in the material, he can make it sing. When he’s not, he’ll throw it under a bus (see also Revenge of the Cybermen).

Elsewhere, I suspect Tom Baker has had a hand in rewriting some of the ‘whippetshit’ he’s been presented with. The Alice in Wonderland dialogue about the treacle well sounds like a Baker addition, as does:

DOCTOR: I feel disorientated.
SARAH: This is the Disorientation Centre

Proving silly moments didn’t creep in with Graham Williams. In fact, as a whole this is a lot sillier than anything since The Time Monster.

Next episode: The Android Invasion – Part Four