Snowpiercer, Season 1 (2020)

After decades of being denied and ignored by global elites, global warming threatens the end of human civilisation. Desperate measures are taken to cool the planet, but the cure proves worse than the disease: the entire globe is plunged into an ice age, with layers of snow carpeting the ground worldwide.

Implausibly, the only successful effort to survive in this frozen wasteland is a massive locomotive, "one thousand and one cars long" that now perpetually races around the planet, using its own speed to power itself. Aboard it, in four categories of privilege - first class, second class, third class and "tailies" - are the final remnants of humanity (as far as they know).

"Tailies" are stowaways who forced their way onto the train just before it began its 'eternal' journey. Quarantined in the final few carriages, they are fed only these strange, glutinous black blocks. The only way out is to be invited, which almost never happens.

But of course, as the show begins, one such rare invitation is extended. There has been a murder in the upper classes and the only trained detective on the train is a tailie. He agrees to help solve the crime, hoping to use the time he spends 'up train' to gather intelligence that the tailies can use to break out of their prison. Of course, the people up train have many more secrets and agendas than just this one murder, and his investigation may stir up forces none of them can control ...

Okay, so first of all to watch Snowpiercer you will obviously need to handwave a huge amount of improbability in the premise of this show.  The train is clearly utterly implausible on a dozen different counts.  I find it easiest to ignore this by telling myself that it's actually a spaceship, not a locomotive.  Essentially that's the same outcome - closed environment, limited resources, utterly hostile external environment - without raising obvious questions like "who is maintaining these thousands of miles of tracks?".

The real question, then, is "if you do handwave that stuff away, is the show any good?".  And the answer to that is a qualified yes.  It's certainly well-acted - the cast is great - and the plot took some fairly satisfying turns along the way.  On the other hand, it's determinedly grim and unpleasant and a bit wearying at times because of it.  You definitely have to be okay with a pretty nihilistic journey if you want to get on board the Snowpiercer.

It's definitely way better than the movie, though.