Based on the Pulitzer Prize-winning novel by Cormac McCarthy, "The Road", faithfully brought to the screen by director John Hillcoat and screenwriter Joe Penhall, is unremittingly stark and almost ceaselessly funereal, with the earth on its last legs following a nuclear holocaust and the sky constantly ashen and grey. Smoke billows from once-thriving towns that are now nothing but a heap of dilapidating buildings, broken windows and rubble. Animal and plant life has ceased to exist and food is a rare, precious commodity to come by. As for humanity, of the few people left, most have turned to cannibalism for their own survival. Out of the barren landscape walk a father (Viggo Mortensen) and his young son (Kodi Smit-McPhee), two of the few "good guys" still around, on a voyage south to the sea's edge. What do they hope to find there? It is hard to say - possibly other life, the kind that doesn't want to have them for dinner. Or maybe they just want a sign of hope to prove to them that life is still worth living. Despite this, the father holds on to a gun with two bullets in it, and instructs his boy on the right way to cleanly and fatally shoot himself through the mouth in case their options run out.

As a book, "The Road" consists mostly of brief but telling dialogue exchanges between the father-son protagonists placed in between generous, ponderous stretches of prose describing the dire environment of a post-apocalyptic planet. In the wrong hands, this intimate human tale might have been beefed up with careless action set-pieces and an onslaught of CGI. Fortunately, director John Hillcoat stays true to what is a dark, but in many ways strangely beautiful, tonal poem. Special effects are used so seamlessly that it is difficult to tell what was shot practically and what was digitally added in post-production. The portrayal of a cold, dying world is immersive and frequently chilling, isolation deeply felt as man and boy wander down roads and through towns and neighbourhoods where life no longer exists and only the ramshackle remains of homes, shops and abandoned cars signal a past that no longer exists.

Flashbacks of the man and his wife (Charlize Theron) before the disaster befalls the planet are fleeting, giving way to the tragedy that destroys their life, just as it does the entire population. The wife gives birth to the boy, but can hardly stand the idea of bringing a new human being into such a futile world. She ultimately loses faith and wanders off into the darkness one night, a suicidal gesture that leaves the man and boy by themselves. This is the catalyst for their journey—it is too dangerous to stay in one place for too long—and the film's impact is strengthened through their unsentimental parent-child bond. Because dialogue is decidedly minimal, much of the love and care that come from them is captured through their actions. The way, for example, that the father gives the boy a can of Coke that he finds—it is possibly the first time he has tasted a soft drink—and how the boy insists his starving papa have a drink too, is immensely moving. Or the way that the father will do anything at all costs when his boy is put into immediate danger by a knife-wielding wanderer. Or the look of horror on the boy's face when his dad won't stop coughing, and he sees a puddle of blood he has spit up. "The Road" is a morose experience, almost guaranteed not to end in a happy-go-lucky climax, but it is the humanity and dignity that these two characters hold onto that keeps things from growing unbearably dour.

In what is a primarily two-actor showcase, Viggo Mortensen and newcomer Kodi Smit-McPhee share a comfortable and trusting chemistry. Mortensen has obviously put himself through the physical wringer as in the unclothed shots of his gaunt, malnourished body, while Smit-McPhee, affectless, emotes with a frequently heartbreaking honesty. That the young Australian Smit-McPhee, eleven at the time of filming, puts on an American accent is all the more impressive. Making a big impression with extremely scarce screen time, an almost unrecognisable Robert Duvall is a haunting force as a withering old man the father and son meet on the road and lend a hand to. Charlize Theron also leaves a memorable imprint as the boy's ill-fated mother, a woman whose reasons for living are gradually outweighed by reasons to give up. Long after her character is gone, Theron's formidable work leaves behind a shadow that casts on Mortensen's and Smit-McPhee's faces and psyches.

The cinematic version may be a step above the source material from a dramatic standpoint. The ending, which comes off as too neat and tidy in the book, seems much more organic on film because director John Hillcoat has slyly been foreshadowing it throughout. With "The Road," there are no aliens, no otherworldly creatures, and no futuristic flourishes, and that's a good thing. The film glimpses what it might really be like if the earth went to hell in a nuclear war. As shattering as the sights are, turning away is out of the question.