Basic story is that "we finally did it!" and every major city in the world has been nuked. There's no discussion of who set the war off or why. And it's chock full of ascientific nonsense.
It's like the people creating the thing just had a Standard Hollywood Global Thermonuclear War Checklist they went down.
I get it, though: GTM is the MacGuffin that traps the characters in a bomb shelter run by Ubiquitous Lesbian Actress (ULA, who is Sarah Paulson) and Kathy Bates. The bomb shelter is where the elites are supposed to ride out the end of the world, but of course ULA and Kathy Bates are sadists and they're screwing with the people in the bomb shelter because they can.
The thing is, I grew up during the Cold War, against a (fairly distant) threat of nuclear war, and was exposed to a lot of civil defense material. All the nuclear bombs in the world, even if used on the same day, would not be enough to completely destroy the environment. 90% of the targets are in the northern hemisphere, to boot.
In the worst-case scenario, where the US and USSR had an all-out thermonuclear war, it would have taken two weeks before the fallout decayed to safe levels. These mooks are still in the bunker after eighteen months.
Of course it's possible that because ULA and Kathy Bates are sadists they are deliberately keeping them there, but then we see a guy come riding up to the bunker entrance in a horse-drawn carriage, and the only protective gear the horses have on is dust masks. At this point, anyone going outside wears dust masks because the air looks like a bad smog day in Beijing, because fallout and nuclear winter blah blah blah etcetera.
There's actually now some question about the possibility of nuclear winter, in fact. It turns out it was never really much of a threat even in a full exchange; mainly it was something leftist scientists had come up with in order to scare Americans into demanding that their government unilaterally disarm.
But even if we accept the nuclear winter scenario, it still doesn't mean the air would be choked with dust, especially not after eighteen months. The air would be reasonably clear; in the nuclear winter scenario there would be lots of clouds, it would be cold, and there would be lots of snow on the ground. Outside the bunker, it would look like an overcast winter day, because that's what it would be.
The nuclear war aspect of the story was a bit unnerving. Now we've descended into what's become pretty typical standard AHS territory. They keep doing this schtick where one person (usually female) has power over a bunch of people, and she does all kinds of cruel and horrible things to them, and they obey her because of that. (Last season's Cult had a man in that role, but the trope was otherwise unaltered.)
The people who are trapped are, of course, a bunch of useless, blithering idiots who don't know anything, so they are easily manipulated. And they're cowards: "Hey, there's two of them and five of us, and they have one gun, so we could probably take them out pretty easily" is a thought that will never occur to any of them--and even if it did, the others would shout that idea down as too dangerous.
Oh. So, you'd rather live in fear, eat one cubic inch of aspic per day as your only meal, and subject yourself to a lot of random cruelty. Okay.
Overall, my impression of this latest outing in the AHS series is "ho, hum", because it's looking like the same old thing they do time and time again, and it's boring.
Even if the "trapped in a bunker" schtick wasn't already done to death, even if they'd done it in a way which was suspenseful and creepy (10 Cloverfield Lane was close), and even if they'd gotten all the physics and science right, this would still be boring because I don't give a rat's ass about any of the characters. We are given literally five minutes in which to get to know the characters before they are thrown into the bunker, and none of them are likable in the least. None of them.
Spoiler: one of the denizens of the bunker is shot dead literally five minutes after he first appears on screen. Am I supposed to care? Does it matter? Was this gay man a brilliant scientist who could have saved the world if Kathy Bates hadn't shot him? No, he was just in the bunker because he could afford to pay the entry fee, like the others. (With the exception of UCLA Boy and His Black Girlfriend, who were put there because they had good genes.)
The other ones in there? Once UCLA Boy and His Black Girlfriend arrive, the residents of the bunker include Spoiled Rich Girl, her Goofy Assistant, Hairdresser, Black Woman, Gay White Man, Gay Black Man, and Joan Collins. (Literally, Joan Collins. That's who plays the character; I have no idea what any of their names are. Joan Collins is Hairdresser's aunt. Or grandmother. Or something.) ULA and Kathy Bates are "staff" and they run the place. Five minutes after the "plot" gets to the bunker, Gay White Man is dead and served as stew. (Oh, that's right--his name was Stuart; I can only remember that because they made a pun on "serving Stu".)
Too much of television these days approximates, "Hey, look at how shitty people are!" It's nothing but nihilist horseshit.
I wish I had the intellect to disassemble things I watch the way John C. Wright disassembles the lastest Star Wars extrusion. In that series of posts, he picks The Last Jedi apart, explaining everything they did wrong in detail. All those problems were things I sensed, but couldn't explain; but having it explained to me it becomes obvious in retrospect. The problems with today's "entertainment" is similar, but I can't describe why; I know only that it's crap. And when you read Wright's critique, you realize that--holy crap, that was what bothered me about that movie!
If I could do that, it would probably also make my own stuff better. *sigh*