Is the human race really worth saving? You get some funny responses to that question. Twice in the past couple of years, acquaintances of mine have suggested that the planet might just be better off without us. What struck me as particularly odd about this statement, at least coming from them, is that they both have kids. If they really believed that sentiment, then they were effectively offering their children up for sacrifice due to the misdeeds of others. Not people they know personally, mind you, but those ones on the news, or in the papers, or on Police, Camera, Action, or whoever it is whose behaviour the media wants to highlight this week and the government wants us to be scared of.

Personally I've always found the end of the world a rather attractive prospect, but I realise that I'm talking largely in storytelling terms, as a situation for apocalyptic novels and films and even TV series (Ah, Survivors...). I will confess, however, that once when I was asked how I'd prefer to die if I was given the choice I replied, a little too quickly, "at the same time as everyone else." It wasn't dying itself I objected to, but the idea that others, people I didn't like or respect, would have the cheek to carry on living after I'd snuffed it. At least if we all went together it would feel a little fairer.

As someone who finds children of all ages largely intolerable, the situation proposed by P.D. James' 1992 novel Children of Men and the 2005 film of the same title should in theory seem rather appealing. With women across the world rendered infertile, the human race, steadily ageing and unable to replenish the stock, is doomed. A world without children and thus a world without a future, at least for humankind. Would that really be so bad? Well if the dystopian vision of a 2027 Britain presented to us in Alfonso Cuarón's masterful futuristic thriller is anything to go by, it doesn't look too rosy.

In Children of Men, the time limit on humanity imposed by this inability to procreate has robbed the populace of an sense of hope and, it is suggested, inspired a society-wide moral and ethical breakdown. I'm not sure I buy that connection in a world in which the earth and its resources are already being shredded in the name of profit with little real thought for how the future generation will pick up the pieces, but I'm prepared to go with it for the sake of the story. The future as presented here seems more a downward development of the Britain of today, or at least the version of it that is presented by the media. Tabloid scare stories about asylum seekers have mutated into draconian government policy, terrorism is rife, law and order is crumbling, and ubiquitous Orwellian viewscreens feed propaganda to every caged-up train carriage and tattered street corner.

Stumbling around in the mire is former activist turned part-time bureaucrat and full-time melancholic, Theo Faron, who only minutes into the film is nearly blown to pieces by a terrorist bomb and a short while later is kidnapped by a resistance group led by his ex-wife Julian. She's looking for transit papers for Kee, an immigrant woman under their protection, and Theo needs the cash and has an old friend in the government who appears just world-weary enough to obtain the documents. But there's a catch – the documents are for two and Theo has to accompany her. A series of plot developments lead to a revelation that will not be a revelation at all to anyone who's seen the trailer or read anything at all about the film. If you haven't you might want to skip to the end of this review now.

Theo discovers that Kee is pregnant and the task he inherits is to help transport her to an off-shore location where she can safely have the first baby the world has seen in eighteen years. Although not a parable per se, the religious and specifically Christian overtones are hard to ignore, a child whose arrival represents possible salvation for mankind, its mother giving birth in a meagre shelter and the mere sight of the infant stunning soldiers into awed, chest-crossing silence. Even the film's title has religious connotations, taken from a psalm that is quoted in the novel but not the film ("Come again, ye children of men. For a thousand years in thy sight are but as yesterday: Seeing that is past as a watch in the night") and a gender-free plural of a famous Christian term for Jesus. But this is never hammered home and sits very comfortably with the more prominent sociopolitical and thriller elements. And these are most impressively realised.

As someone who has railed against CGI in the past, I feel I should qualify the apparent turn-around I am about to make. The possibilities offered by this tool are, at its present stage of development, seemingly infinite, but too often filmmakers choose to run with that freedom like greedy kids in a candy factory, creating sequences that exist largely to draw attention to themselves, toppling the film off the ledge of plausibility in the process. For my money CGI really fulfils its potential as a cinematic magic wand when you genuinely cannot tell whether you are looking at a constructed set, a model, a computer generated image or a blend of all three. Such is the case here. Right from the opening scene, the damaged Britain of 2027 is visualised with startling realism, with entire streets transformed and attention paid to the smallest of details (blink and you'll miss the video advertising that adorns the side of London buses), creating an almost documentary-like sense of a once great city in moral and physical disintegration.

Clearly taking the advice offered by his friend and fellow Mexican director Guillermo del Toro to always serve the story, Cuarón makes the characters and narrative his priority. The twists are perfectly timed and the predicted arcs not always followed – we expect sacrifices, but at least two come out of nowhere, and by the second half the tone is dark enough to ensure that there are no guarantees of a positive outcome for Theo's quest. The performances are largely excellent, the real revelation being Clive Owen as Theo. An actor who on some previous occasions looked in danger of joining Rupert Everett and Jonathan Rhys-Meyers as specialists in gaunt, moody cheerlessness, here he compelling holds centre stage, a seemingly unlikely hero who rediscovers a cause and the will to risk all for it. The supporting cast, which includes site favourites Julianne Moore, Peter Mullan and Danny Huston, are all fine – the only one I'm not sure about is Michael Caine's dope-growing, holed-up-in-the-woods ex-protestor Jasper. He's clearly having fun with the role and the performance is enjoyable enough in its own right, but he always felt to me like Michael Caine dressed up as a hippy, the sort of left-wing idealist the actor once fled the country to avoid. I can't help thinking that there are many lesser known character actors who would have better suited the role, but who would, of course, have been less of a box-office draw.

Cuarón demonstrated both his cinematic dexterity and skill with performers back 2001 with the splendid Y tu mamá también, and after a trip to Hollywood for Harry Potter and the Prisoner of Azkaban (a movie I have so far failed to see – odd that), he makes the transition from Mexico to Southern England as if he's been boning up for the stiffest nationality test imaginable. Part of the film's uncanny sense of the familiar comes from keeping the future rooted at least partly in the here and now – even at its most extreme the imagery is still instantly recognisable, as when Theo ducks and dives his way through a battle-torn estate, recalling news footage of civilians caught up in street battles in, well you name your recent war, and shot (in a breathtakingly executed nine-minute take*) as if captured by a TV news cameraman also in fear of his safety.

The action is always impressively staged, and more than once I was left unsure whether I was watching stunt work or very smart CG trickery. There are memorable and inventive touches texturing almost every scene, from the Diana Spencer-like outpouring of grief at the death of the world's youngest person to the contemporary protest headlines on the clippings in Jasper's house, or the getaway car that has to be freewheeled and bump-started to secure a precarious escape. From its opening scene, Children of Men tells an intelligent and well constructed story with fully rounded characters in consistently gripping fashion. Its dark outlook is refreshingly welcome for a film with a Hollywood-sized budget, a big studio distribution deal and three Oscar nominations (inevitably two of these are technical gongs), although I couldn't help wondering if the film would have attractive similar financial backing if the novel had been set in an American city a few years from now...

The cinematography (courtesy of Cuarón regular Emmanuel Lubezki) is very much part of the film's distinctive aesthetic, key components of which are a steely palette that is deliberately lacking in bright colours, and tweaks made to the contrast and brightness levels that appear that give even sunlit exteriors have a hint of gloom. All of this is reproduced on DVD very nicely, with colour, contrast and sharpness looking dead right to my eyes. The framing is 1.85:1 and the picture is anamorphically enhanced.

The 5.1 track has impressive clarity and decent frontal separation. The surrounds come to life during key scenes, especially in the 9-minute combat shot, but it's somewhat less aggressive than you might expect. It's worth cranking the volume up to get the best out of this.

Men Under Attack (7:36)
I can't help thinking it a bit cheeky to have a section on the main menu titled 'Bonus' that only has one, 7-minute inclusion. It's a damned interesting one, though, covering the shooting of two of the single-take action sequences, including a complex in-car shot that runs for 12 uninterrupted minutes.

The lack of extra features is most definitely what lets this disc down, as this film cries out for a commentary track and detailed coverage the production design, stunt work, special effects, and even the novel itself. One for 2-disc re-issue later, then?

Camus reviewed this film on its cinema release last year (you can read the review here), and different though our viewing habits tend to be, this is one we seem to have found ourselves in total agreement on. I've been surprised by the more negative reactions I've encountered in some quarters, although its failure to ignite at the US box-office should not be surprising when a sizeable proportion of the audience still seem to only respond to happy happy happy. Children of Men is a rare and fine example of film with indie sensibilities made on a mainstream budget, and one that really deserves to find an appreciative audience. The DVD sounds good, looks very good, but is left waiting for a set of extra features to do it justice.

* Apparently this was indeed a single, unbroken shot, the third of three attempts at this extraordinarily complex sequence. The blood splatters on the camera lens that vanish were digitally removed for the final part of the sequence.