Doctor Who: Chase the Night

Still travelling through E-Space, the TARDIS arrives on a planet that, like Mercury, is partially tidally locked to its star, resulting in an unusually long day. Unlike Mercury, the star in question is an intensely hot blue dwarf star, with the result that the planet's night side is habitably warm but the day side is lethal. The only way to stay alive for long is to move at a constant speed of 9 mph, chasing the night to outrun the deadly burning dawn.

That's the basic setup, and there are plenty more science fiction ideas to add to the mix. Many of these relate to the planet's biology, so it's probably fair to say we're right in my wheelhouse here. Indeed, there's even one that, while based on real-world biology, I haven't personally seen used in a science fiction story before. This does involve some technical terminology, much of it courtesy of K9, but it's explained well enough that there shouldn't be any difficulty following it.

Aside from the unusual setting, however, the story itself is a strong one, with a constant sense of tension driven by that need to keep moving to avoid destruction. There's a good mix of guest characters in a culture that has some parallels with that in TV story Full Circle but that still has plenty of differences. It even raises some moral questions about what you would do to survive in such a place - although the way the main antagonist solves them is clearly not the right one.

With Adric being useful, rather than annoying, all the regulars are key to the plot and there's some good interaction between Romana and the Doctor. Perhaps it's appealing to my particular tastes but this is one of the strongest 4th Doctor audios for a while.