"...becomes real..." 'Real' has always been a contentious word when it's movies you're talking about but then is what you feel inside a cinema dwarfed by an engrossing movie real in any way? Can a two mile plastic 'someone else's' light dream invoke real feelings? Hell, yeah! You should have seen my face when John Hurt gave birth in Alien... I may not have been in fear of my life (like the rest of the characters) but the emotion of fear was real. I think. We cry in cinemas. Real tears? Our palms sweat. Real sweat to be sure. But is the experience valid in the sense of a 'real' experience? Not to cheapen the word in any way but Cronenberg's A History Of Violence is the real thing.

Some movies just stick in your craw in the best possible way. I came out of A History of Violence seriously jolted and with an even more profound respect for David Cronenberg than I previously had. He also has great hair but (I believe) this is not relevant. That's a whole mess of respect. I was in the hands of a 'real' film-maker, a storyteller who knew exactly how to communicate, through his work, the vagaries of the human condition which blossom in hostility. And like all good movies, A History Of Violence allows you to burrow through its subtext and metaphor for weeks afterwards.

Two men amble out of a motel. The heat and insect drone is oppressive. Their dialogue is banal and interspersed with complaints about the weather. The older man grumbles about their lack of water for an upcoming car journey and the younger man goes back into the motel to fill up. It's all shot in one long, indolent take. I can't say why, but my attention was well and truly held, gripped you might say, hemmed in by the sounds and images of this amazing piece of direction. The mood felt wrong, ominous, discordant. Of course, you do not attend a screening of a film with the word 'violence' in the title and look forward to gingham dressed children singing about their love for their grandparents. That's real horror. I knew these guys were no good. They were cold on a canvas of searing heat. They were born without the ability to care.

The first cut finally arrives (we are now inside the motel) and Howard Shore (the composer, a long way from Middle Earth) is starting to hint to us that things are most definitely not right. The younger man passes by the check in desk, where sprawled and bloodied sits victim number one. The victim's wife lies at his feet in a pool of blood. It's horrific carnage and not any different to what any other movie may offer up as an image of murderous mayhem but having the scene presented in this way with that terrifically stifling build up, makes it somehow more real. There's that word again. These men are sociopathic, a fancy word which means they have no empathy or regard for others and therefore are able to kill without remorse or compunction. As the younger killer's filling the water container, the murdered couple's sobbing daughter steps into the lobby. A gun is released from a waistband...

This isn't the shock, almost comic squib slap of the little girl who wanted a vanilla twist in Assault on Precinct 13. You don't see the girl die. Cronenberg uses a shock cut to get the point across. These acts are not action movie set ups, people dying – to be avenged by the hero in the final reel. They have been presented to show the banal nature of the sociopathic killer. They kill. That's that. Shore's bleak score almost soothes us because it reminds us that it's still only a movie despite the darkness and metallic loneliness of his Silence of the Lambs-like underscore. I wondered about Cronenberg's musical intentions here, feeling that no music would have been more appropriate but Shore's score is dark and cold enough to only add more horror not dilute its 'reality'. We know these guys now. Bad to the bone...

The cut from the murdered girl features another girl screaming after having had a nightmare. Sarah Stall (played by Heidi Hayes) is the only weak acting link in the film (she pronounces every word distinctly and only actory kids do that, not real ones) but this is a minor quibble. Everyone else delivers stand out performances. The Stall family is a very happy family. They are happy in that 'even the teenage son comes to comfort the little girl' type of happy. It's very sweet (hah!) and utterly – some may say coldly – designed to have the impending horror car crash into them twice as hard. It's the American dream – the family, the town, the job, the serenity. She's a lovely Mom (Maria Bello), he's a lovely Dad (Viggo 'Aragorn' Mortensen). These are simple folk who run a diner in town. In anyone else's hands, these moments and full blown scenes of contentment would grate and become archly dull all too fast. But because we are so wired from that extraordinary opening, we are thankful for the respite. Cronenberg lets his characters take their time (how refreshing is that?). If someone gets in a car we see him fully get in it and drive off. It is the cinema of thought. Moments that would send Michael Bay scuttling to his razor tool in the edit suite, are kept intact and they are all the more powerful for it.

Cronenberg lets his movie breathe and thereby allows him to ratchet up the tension and suspense. We are looking into actors' faces not at them. The big difference is there is so much more going on when you're given a chance to look behind the eyes. We know our lovely family has a date with the sociopaths. We know that this violence will change everything. I was reminded of Dennis Potter's Brimstone and Treacle in which a girl in a coma is brought out of that coma by being raped. The Stalls (subtext much with the name choosing?) are in a coma, a soft space of domestic tranquillity. The family is about to be collectively wrenched from their cushions and then once wrenched, like a snapped ligament, they will never be able to regain what was lost.

I have not been held so firmly in place watching scenes that out of context would be simply banal. Context changes everything and Cronenberg knows this. So while we while away the Stalls' bliss we are slowly getting the family under our protective wings. There will be tears before bedtime. There will be blood on the moon. All I knew about the movie was that Tom Stall (Mortensen) does something heroic which turns out to be the metaphorical equivalent of your dad lifting up a rock on the beach to find all sorts of life scuttling away, exposed to the harsh light of day. I guess I was waiting for this event so the movie could extrapolate from it. In the meanwhile, Stall's son Jack (Ashton Holmes) is being bullied big time. Cronenberg plays cleverly with audience expectation here. How extraordinarily satisfying it is, seeing the bullied best the bully. It's just as satisfying here except we are invited to find this violence abhorrent however 'justified' it is in narrative terms. It's an act his father can't condone but the son gets a slap for his troubles. He truly is his father's son but no one knows that yet. The normal family's life is slowly beginning to unravel.

Edie Stall (Maria Bello) decides to treat her husband to a fantasy – an illicit, sexual treat by having both parties pretend they are both teenagers again – having sex in her parents' spare room. Dressed as a cheerleader (go, that American dream!), she jumps her man (who quizzically asks what this other woman has done with his wife, a question wrapped up in a few dozen irony jiffy bags) and the following scene is adult and almost coy despite how intimate it is. Each loses bits of significant clothing as they writhe into a sixty-nine but what's so refreshing about the best sex scene since Don't Look Now is that it's still to come (so to speak). This coupling and the gentle nature of it is intended as the yin to a future scene's yang. We'll get to the yang in a moment.

The sociopaths arrive in town and their malevolence drips off them like oil. The first to recognise this is the school bully who gives them the finger after a driving incident. The finger lowers and the face says it all. He knows these men are capable of, for want of a better word, 'evil'. They enter the cosy world of Tom Stall's diner (Tom is closing up) but they get their coffee. Sexy Beast played very interesting games with the politics and practicalities of intimidation and here we see the US equivalent. These men are soiled with amorality and director Cronenberg is about to step over a very fine line. Can a movie about violence show violence in a glorified Hollywood way and still ask us to be sickened by it? I'm unsure what Cronenberg's big theme is (see the opening quote for the general theme) because I'm not sure what is real in his own context. The point I'm making is that the violence in the diner is very slick, sharply cut and owes its affect to the editing. It's more Bourne Identity in style than 'real' in any sense but Mortensen is credible. And that's crucial. We get a nasty cutaway (this is what a man looks like after he's been shot in the head) and I'm happy to say there were groans of disgust from the audience I watched it with. So there should be.

An injured Tom goes back to his life but now he's a hero. That's not good news for someone who genuinely wants to remain anonymous. Suffice to say, his own history of violence comes back to haunt him (Ed Harris plays the principal memory jogger, eerily creepy as a one-eyed mobster). Always throughout this exact and bold movie, you are left with wondering how the family are going to deal with the consequences of their and others' actions. That's the key. You care enough to invest in them. When Tom needs to scourge all his demons, he does it in a Hollywood way but because the film has taken you this far, you tend to go that far with him.

After a cathartically violent confrontation with those who sought to drag Tom back to a past he thought he'd exorcised, things in the Stall family are not as they were. The sexually frisky cheerleader is now an ambivalent wife with a husband whose past now defines him. She is scared and unsure. She has an altercation with him as she climbs the stairs and this violent encounter that culminates in full, passionate sex (on the stairs, ouch) is amazing in all sorts of ways. She has instigated it and it is she who rejects him after his climax. The most important part of the scene is we clearly see her pulling Tom towards her. Violence, sex, desire, repugnance, regret, need, affection. Cronenberg can cover all that on the stairs!

Stall (pushed by outside circumstance) does what a man has to do. Returning to his family, he is accepted and/or rejected but the final cut (a cut to black) is most telling and by far the most interesting cut of the film. His life is worth living based on the decision made in that black space – ultimately in our minds. A History Of Violence is an adult film about adult issues and themes. It is directed with great and quiet skill and performed so honestly, you feel you've actually met these people. It's going to camped out in my cerebellum for a few months yet...