The research team at the facility will have found or discovered an ancient virus from one of their core samples from another period of life.
Upon being exposed to it, it spreads fast and drives them crazy, and makes them follow some sort of herd mentality, to where they kill themselves like lemmings.
That's my guess, and I don't think there's going to be anything supernatural. If you watch the intro graphics, they show some sort of vault door that looks like it's dug down into the ice, that's probably where whatever experiment is taking place.
There are a lot of other science fiction or horror stories out there that have used the same concept. If it ends up being different then so be it and that'll be great, but that's what I'm placing my bet on. I'll watch it because it's well produced and I have at least enjoyed the other seasons in some capacity because I thought they were original and well acted.
Surprisingly there was a Scandinavian show that I'm afraid might be the same goddamn deal or at least a version of what they're currently doing that came out a good number of years ago. I do not remember the name of it. I'll try to figure out what specifically it was but after watching the first episode of this new season it really reminded me of that particular show. I think that one had maybe two seasons and it was pretty good, but I'm getting a lot of the same thematic tones.
Anyways I hope it'll turn out decent and I don't watch a lot of TV nowadays, so if I'm going to I'd like it to be worth watching.