There’s something almost quaintly Cold War–ish about the setup of “The Divide,” which traps a dozen or so residents of a Manhattan high-rise in a cellar bunker after the city has been nuked by parties unknown. It’s the sort of post-apocalyptic scenario that popped up throughout the ’50s and ’60s in films like “The World, the Flesh and the Devil,” “The Bed-Sitting Room” and “On the Beach.” Of course, those movies didn’t have raping and corpse-dismemberment and box-cutter torture, so it’s not like “The Divide” isn’t making an effort to keep things contemporary. The film opens with the destruction of New York City, after which a dozen or so tenants swarm into the basement, where building super Mickey (Michael Biehn) has assembled a fairly elaborate shelter, complete with water, canned goods and even a septic toilet. (He also manages to keep electricity going for weeks after the nuclear incident, a miracle of science that’s never explained.) You can pretty much guess what happens next — supplies dwindle, the residents turn on each other, alliances form, violence erupts. First-time writers Karl Mueller and Eron Sheean basically graft “Lord of the Flies” onto “No Exit,” but French horror director Xavier Gens (“Frontier(s)”) keeps things tense for most of the running time, even though there’s a finite number of ways to show people losing their humanity and giving in to their more beastly nature. The cast is peppered with young TV vets like Milo Ventimiglia, Lauren German and Ashton Holmes, but two of the more seasoned players make the biggest impact. Biehn effectively keeps us guessing as to whether or not his building manager, now suddenly the man in charge, has everyone else’s best interests in mind or not. Rosanna Arquette, who established at least as far back as “Crash” that she’s valiantly vanity-free when it comes to on-screen sexuality, takes us on a heartbreaking arc as we see her character devolve from devoted mom to helpless play-toy for the alpha males. One of the film’s most effective moves is almost never to stray outside of the shelter -- in fact, “The Divide” loses its way with a quickly-abandoned subplot about what might be happening in what’s left of the surface world, the intrusion of which winds up being a plot device to put a haz-mat suit and a lethal weapon into the hands of the cellar-dwellers. Even if you’re not necessarily a fan of watching civilized people turn into teeth-gnashing, garment-rending troglodytes, there’s plenty to like in “The Divide.” It’s by no means a complete success, but it knows how to make you squirm.