I tend to find dystopian science fiction disappointing. All too often, it transpires that a single catastrophic failure – political, environmental or military – has resulted in Doom and, I dunno, I think I’m just too bullish on human ingenuity and resilience to find that convincing. People seem to have always thought that the world was going to hell in a handbasket, even as many objective measures of human wellbeing – infant mortality and literacy, for example – have steadily improved. I don’t believe progress can be derailed that easily.

The few dystopian fictions that I really admire – the usualsuspects, basically – are less attempts at prediction, more allegorical warnings of present-day ills. But that approach is fraught with difficulty, too: I find ham-fisted, half-baked morality tales even more tedious than pointlessly pessimistic apocalypses. Even when allegories are done well, a dystopian approach can be overkill: it’s a cinematic analogue of Godwin’s Law. I already understand that prejudice/fascism/pollution/cyborg killing machines are bad, m’kay?

And since I’m not the kind of guy who likes to sit in his bomb shelter fondling small arms and counting cans of sweetcorn, I’m not particularly interested in watching civilization disintegrate for the sake of it. A post-apocalyptic landscape can make a decent backdrop for a story, but rarely captures my interest in its own right. It’s not enough that the world should end: it has to end in an interesting way. The first example that leaps to mind is Brian Vaughn’s Y: The Last Man, in which the world doesn’t actually end, but civilization certainly stumbles a bit.

Like Vaughan’s comic, Children of Men postulates a future in which a single social element has been mysteriously removed: in Y it’s men; in Children, it’s, well, children. This, of course, sets up an obvious plot in which the first pregnancy in eighteen years becomes the target of warring factions, and the expectant mother has to be shepherded to safety by a conflicted everyman. But since Alfonso Cuarón’s adaptation of PD James’ novel is neither didactic nor simplistic, there’s both more and less going on than that.

More, because the infertility pandemic is only one of the ills that have beset humanity: totalitarianism, armed conflict and environmental collapse are all suggested as contributors to the film’s version of the Grim Meathook Future. And it’s a startling believable vision, thanks to richly textured set design and convincing performances – as well as distinctly British locales that helped me out a lot in suspending my disbelief. I’m still not wholly convinced by the world it depicts, but it’s close enough to be scary. And it is very scary.

Less, because – like much of my favoured fiction these days – Children of Men offers few clues or answers. There’s no explanation for the childlessness, or for the miraculous pregnancy – this isn’t the kind of apocalyptic thriller in which the race is on to identify a magically curative antibody. The plot twists and turns a little, but the narrative’s force really comes from the cinematography and insistent pace. Even the ending is inconclusive: all the viewer is left with is hope. And that, more than all the careful world-building, is what makes Children of Men enduringly memorable.