No Country for Old Men, 15

It's been a while since Joel and Ethan Coen seemed really to keep faith with their material. We've long become used to them as cynical comedians, to drastically diminished effect in their last offerings, Intolerable Cruelty and The Ladykillers. So if the grim thriller mode of Fargo and their debut Blood Simple are your idea of a proper Coens film, No Country for Old Men may strike you as a signal return to form.

Based on Cormac McCarthy's 2005 novel, No Country is serious indeed, a matter of life and death – or of money and death, which is graver still. Its trigger is a classic thriller device: a man finds a bag of money, then has cause to wish he hadn't. In the Texas desert in 1980, Llewelyn Moss (Josh Brolin) stumbles on the aftermath of a mob massacre and walks out with a briefcase containing two million dollars. Thereafter – following a single, ill-judged act of compassion – he has the proverbial hellhound on his trail.

That hellhound is the mysterious Anton Chigurh (Javier Bardem), in effect the living embodiment of slaughter, whose ghoulish weapon of choice is a cattle-killing rod powered by a hefty gas cylinder. Chigurh executes more or less anyone he meets, occasionally allowing potential victims to decide their fate on a coin toss: they pay the price of survival by listening to his gnomic ramblings about destiny.

No Country is a relentless chronicle of brutal slayings and narrow escapes, punctuated by rueful mutterings by the film's presiding conscience Sheriff Bell (Tommy Lee Jones), a good man who'd like to clear up this sorry, bloody mess of a story that's landed on his desk.

Without doubt this is a classy, masterly executed film. It's shot impeccably by Roger Deakins, who spreads blasted desert vistas across the screen like dry parchment, and edited by the Coens (aka "Roderick Jaynes") for maximum tension. We get action sequences that you never knew the brothers were capable of, and stakeout scenes of jaw-tightening tension. There are the sort of small, telling details that it takes the Coens' peculiar attention to pick out: scuffed lino in a murder scene, a wrapper gently unscrunching on a counter top.

Yet there are also Coens touches that might have worked in their more facetious films, but break the tone here: Moss wakes up bloodied in a Mexican town, serenaded by a band of chubby mariachis. When Chigurh plays psychological cat-and-mouse with a garage proprietor, the effect – following the novel, to which the film is pretty faithful – ought to be chilling as well as revelatory of Chigurh's philosophical perversity. Maybe because it's what we expect of the Coens, the scene comes across as absurdist farce, inviting us to relish a satanically cool character messing with a bemused hick.

Some of the casting is inspired. Josh Brolin is a taciturn old-school cowboy whose profile looks as much a part of the Texas landscape as the surrounding mesas. We get a softer Tommy Lee Jones than usual, his aggrieved frown suggesting for once that he'd rather brood over his coffee rather than throw it in someone's face. And Kelly Macdonald, as Moss's wife, brings the film a last-minute surge of wounded humanity in her affecting final scene.

But I can't help feeling the film is ultimately hollow. In Cormac McCarthy's novel, we see a high literary writer using the hard-boiled thriller as a hanger for his metaphysical and state-of-America preoccupations. While some of those concerns persist, the movie is essentially a straight genre exercise. McCarthy's Chigurh is a barely defined silhouette, but as played by Javier Bardem, he takes on very solid form: a lanky streak of black denim with red-rimmed eyes, a bullish countenance, distracting Castilian – rather than Mexican – inflections, and a ludicrous pageboy haircut, already much publicised as the film's definingly zany Coen touch. As indestructible as Freddy, as alien as the Alien, Chigurh becomes another of the Coen collection of grisly goofballs.

When it comes to the inexorable machinery of the tragic thriller, we were spoiled last week by Sidney Lumet's masterly, no-frills Before the Devil Knows You're Dead, which illustrates, as great film noir often has, how ordinary people with ordinary weaknesses can easily open the wrong door and casually walk straight into hell. The Coens' country is hell from the start, already inhabited by freaks, demons and lost souls. I'm not sure that this mythic scope and the action thriller are a natural fit – or if they are, it's Cormac McCarthy's fit, the Coens' less so.