Now here's a story I loved on first watch, and only grew on me with time. Oxygen is a real gem, and I've been glad to see it getting some more serious attention and appraisal in the years since its broadcast.

One of the things that makes this story so unique is its uncompromisingly "realistic" take on space travel. Rather than some sort of cosmic ocean, here we see the vacuum itself as an antagonist in and of itself, even if an unconscious one, and are reminded of the fragility of human existence, hugging the skin of our blue planet. The frozen corpses throughout this episode are really grim stuff, especially for Doctor Who, but used so well that it never comes across as gauche.

And there's the political angle, of course. This is probably the most uncompromisingly anticapitalist story in Doctor Who's history (with perhaps The Sunmakers as the only exception, as in this one they just give the bosses an earful instead of chucking them off a building). Capitalism, like the vacuum, is presented here as an impersonal force that's utterly inimical to human life. The difference, in the end, is that capitalism was created by humans, and so it can actually be vanquished.

That aside, Bill and the Doctor are both fantastic in this one, between the Doctor's blindness (and what a twist at the end!) and poor Bill grappling with what seems to be her most dangerous adventure yet at this point. I was biting my nails over the scene where she appears to get electrocuted by her suit, back when I first watched this.

An incredibly cold, scary, isolated story - and with a nice message to boot. It's one of my favorites of its era.