Children of Men That “carry around a sack of flour” assignment? Harder than expected.

I'M GOING TO CUT right to the quick: Children of Men is the best film I've seen all year, and you should go see it.

Okay. There's more to say beyond that boiled-down imperative, but that needed to be dealt with, gotten out of the way. We're good? You'll see Children of Men? Okay. Glad that's settled. Sorry for the kind of dickish bossiness, by the way. But I only get that way when I really care about a film, which, in all honesty, doesn't happen nearly often enough; rarely does a new release come along that makes me feel justified in straight-up telling you to go see something.

And it's especially not a regular thing with science-fiction movies. Usually sci-fi movies get a bad rap, which is too bad; what's worse is that they almost always deserve it. It's an embarrassingly simple recipe: Come up with a plot that involves, however tangentially, spaceships or time travel or clones (ideally, it'll have all three), then devote a good percentage of the budget to flashy CG. Almost inevitably, such films are wildly successful: A genre both defined and limited by its tropes, sci-fi has settled into an easy niche, with cheap straight-to-DVD films perpetually repeating on the Sci Fi Channel. But okay, still: There is sci-fi that matters, that defies the genre's clichés, that affects people regardless of whether or not they can recite Star Trek's episode numbers: films like Stanley Kubrick's A Clockwork Orange, Ridley Scott's Blade Runner, and, yes, Alfonso Cuarón's Children of Men.

It's two decades from now, and women can no longer conceive children. The reason is unknown, and frankly, unimportant: Children of Men is concerned with the aftermath of this development rather than impetus. What is evident is that humanity's days are numbered, and for humanity's aging remnants, the world has become a far uglier place: Nations rage through war as terrorists strike, governments clamp down with martial law, immigrants and refugees are feared and detained, and the upper classes recline in comfort while poverty and strife envelop everyone else. It's a dystopia that borrows as much from Orwell as it does the Bush administration—as rotting elementary schools lay eerily abandoned and suicide kits are sold over the counter, humanity accepts its end, though it refuses to do so peacefully.

Enter Theo Faron, who, as played by Clive Owen, is as weary and nihilistic as anyone who's sane would be in this world. Theo spends his time talking to Jasper Palmer (Michael Caine), a pothead intellectual who's accepted humanity's demise with a sort of jovial resignation. And amid all this chaos and turmoil, a ghost from Theo's past emerges: Julian Taylor (Julianne Moore), a rebel who needs Theo's help in protecting Kee (Claire-Hope Ashitey), a young woman who, inexplicably and incredibly, is—natch—pregnant. Soon, Theo is wrapped up in a race to help Kee, scheming with corrupt government agents, sprinting through battlefields, and trusting a fanatical activist (Chiwetel Ejiofor).

Director Alfonso Cuarón—who has previously impressed with the spirited, sexy Y Tu Mamá También and the only decent Harry Potter flick, Harry Potter and the Prisoner of Azkaban—drenches everything here in a somber, grimy gray, with overcast skies hanging over squalid ghettos and silent forests alike. With long, patient shots, Cuarón lets the story's smart, intense action unfold in a strikingly organic and terrifying way—yet as comfortable as he is with his excellent cast and captivating story, Cuarón doesn't hold back, with jarring scenes of warfare and terror in a world gripped in unimaginable cynicism. Children of Men is dramatic, moving, and even shocking, but it's never pushy— Cuarón, through subtle use of special effects and a solid script based on P.D. James' novel, creates a film that feels almost documentary-like, creepily tangible and prescient.

But while the deft skills of Cuarón ensure that the film is practically engaging—Children of Men is nothing if not extraordinarily well constructed—like all great films, it really works because it resonates: The implications and echoes of our own world in Theo and Kee's are what make Children of Men something more than just staid sci-fi. Children of Men is a stunning piece of science fiction, yes. But like the best science fiction, it's simply a stunning piece of fiction, period.