As I picked this, I felt it my duty to watch it. But then I picked it as the worst Terry Nation episode I could come up with, and I stand by that assessment. (I won't read Fiona's MtD expose' which I note has arrived as I was composing this...)
First season B7 (in which all episodes were written by Nation) strikes me sometimes as a set of experiments in writing in different styles/genres. One can almost imagine Nation sitting down and thinking well, 13 episodes, Robin Hood in space, when was the deadline, god, last week... what cliche's can I rehash... and raiding the cupboard of action/adventure (SLD, Project Avalon), Star Trek (Duel, Deliverance), evil/mad scientist-style sf (The Web, Orac) &c &c before finally pulling out the Agatha Christie....
So we're treated to vintage detective fiction in the Poirot style -- mysterious series of murders, closed system crime, outsiders happen by and get pulled in to solve the mystery, events cast suspicion on each member of the group in turn, before finally plot device clue reveals the answer .... All very well, but the tension here is entirely lacking because there's no inherent threat to the crew of the Liberator. (The external tension devices [dark corridors, music track] are all very well but can't really amplify what just isn't there in the first place.)
I'm not even convinced that the 'spacisation' of detective fic would have been novel at the time -- weren't there some Asimov novels that took this idea (eg The Caves of Steel, published 1954)?
The original intent here was to discuss Terry Nation's writing, so we can safely ignore one of the worst aspects of the episode ... the terrible acting by the extras (with their budget they could either hire one or two extras who could act or 8 who, in the main, couldn't).
What we can't ignore is the succession of lame plot devices, not to mention gaping plot holes (how does Liberator get back to the Ortega without going through the meteor storm?, why does Avon confront a known murderer without a single thought as to the consequences?), and rather odd characterisation (Blake destroying the Ortega).
And a couple of wibbles. The sub-light-restricted Ortega will take 5 months to get to Destiny, while Liberator, the fastest ship in space, will take 4 days -- assuming months are earth length that's only a 40-fold difference, which doesn't seem to me to be enough.
There seemed to me to be a strong implication that the fungus from Hell might be some kind of Federation colonisation device, which in view of later episodes (Children of Auron, say) seems rather plausible. In which case, there's almost certainly a quick and cheap way of killing the fungus once the existing colonists have been driven away/died. This type of possibility would seem to make for a much more interesting/pointful episode than watching Avon striding around with his hands behind his back imitating Poirot...
So... sloppy hack writing ? Definitely. Deep meaning ? None that I can see. Entertaining ? Not really.
Tavia