I honestly think this may be one of the most extraordinary episodes in the history of 'Doctor Who'. I don't necessarily think it's good for all that, although it's not nearly as bad as its reputation, but it is genuinely something astonishingly out of the ordinary. And that's by the standards of a program that I consider to be one of the most innovative shows on television.
There's a manifestly improvisational quality about it. Obviously, everyone is aware of the transcendently strange credit, "Insect Movement by Roslyn de Winter", and it's clear that the actors took a hand in coming up with ways to bring the script's audacious concept of truly alien aliens to life. But it seems to extend all the way through the piece, from the direction to the script to even the way the regulars behave. It's as though they're playing a child's game of Let's Pretend, where anyone can come up with a new rule for the story and everyone has to follow along. "I put a golden tuning fork on you, that means you have to pretend you're hypnotized!" "Okay, but I used the astral map from the TARDIS to neutralize it, and we have the spider that the Zarbi is afraid of!" Everyone seems slightly surprised by everyone else's lines, as though the story is being created on the spot.
It's a bold decision, one that risks failure at just about every turn. When the Optera are introduced, there's a manifest sensation that the plot is teetering on the edge of a total collapse into absurdity--they're strange, hoarse, grunting, hopping little men that the story tries to present as a terrifying threat to Ian and Vrestin despite all the visual evidence to the contrary. Russell and de Winter instinctively realize that the only way to survive a scene like this is to play it absolutely straight--if at any point they treat it with less than total dignity, we're going to lose our conviction in it as well. Which very nearly happens anyway, because de Winter's way of playing it "absolutely straight" is to do her best butterfly dance and talk like a particularly fey elf from a local stage production of 'Lord of the Rings', but Russell doesn't flinch at the weirdness. He's being given the most thankless role he's ever done on the series, but none of that shows in his performance.
In the end, the whole thing coheres in a weird fever-dream sort of way; you can just about understand what's going on, if you watch it only one-quarter with your eyes and three-quarters with your mind, but you can't imagine quite how it wound its way through the creative process to make it to the screen as a piece of television. It's like watching an experimental, avant-garde play...very bold, very courageous, with a lot to applaud, without ever necessarily being any good. And yet it's so compelling that you can't really call it bad either. And to think, there's two more episodes of this...