This blog comes with the generalized warning that any post may contain spoilers. That is especially true of these Space: 1999 posts. So if you haven't seen this episode, intend to watch it, and therefore don't want spoilers, then don't read.
The moon encounters a ship that's signalling it has a plague. Despite the plague, its captain signals she must land. It turns out that the "plague" is a Psychon -- presumably the only surviving Psychon other than Maya -- who is being held in stasis because of his criminal nature and his hypnotic ability to control others.
There's too much in this episode that doesn't make any sense. From the way Dorzak is portrayed, to the unexplained fact that Maya's perception of him is so terribly wrong. Perhaps if there were some action, then the logical flaws could be forgiven. But as it is this is just slow-moving and boring. It's supposed to be a kind of three-way chess match between the Alpha crew, Dorzac and Sahala (the alien ship's captain). But the twists and turns are largely predictable.
I suppose that if I want to find something good to say about this episode (which I don't, but what the hell), I'll note that I like the way they worked Tony's beer-brewing into the story-line. In fact, a part of the plot turns on Tony's beer. Still, though, no follow-up on Helena's sculpting.