Doctor Who does a bottle episode for the first of (as of 2025) 8 times in the franchise's history. And it's pretty good!

OK, it's not perfect. I don't know what they were thinking with Susan and the scissors, and there's a bit where William Russell seems to be over-acting. But the story itself is fascinating and tightly written. No capture-release cycle here!

It also provides some character development for The Doctor, and his conversation with Barbara near the end of the episode is quite touching. I also find his first line interesting. In the first episode, he says that he and Susan will one day return home. Here, he admits that he can't, but only whilst half-unconscious and not to Susan, but to Ian and Barbara. It's my belief that he's protecting her from the truth, something we know he does as later in the story, he tells her and Barbara that they have ten minutes to live, but admits to Ian that it's five. He thinks he knows there's no way to survive, but wants them to die before they know it's happening.

I can also see, looking at this and the other rare Classic two-parters, why RTD chose a 45-minute format, with occasional two-part story, for the revival. The pacing of this story, which must be close to that runtime with the first closing, second opening, and recap cut off, is much tighter compared to most Classic stories, but never feels rushed.