Cillian Murphy is the coma victim who wakes up to find that a deliberately leaked virus has turned Britain into a nation of raging zombies. Hooking up with a handful of desperate survivors, Murphy's Jim flees London to seek sanctuary up north. But are they any safer with army major Christopher Eccleston and his paranoid platoon? Nasty surprises spring from every which way in Danny Boyle's splendidly twitchy apocalyptic horror. The surprises even keep coming after the end credits with an alternative ending that Boyle and writer Alex Garland are equally proud of.
When virus survivor Mark (Noah Huntley) tells former coma patient Jim (Murphy), "I've got some bad news," you have no idea how much badder it's going to get.
Mark and Selina (Harris) have rescued cycle courier Jim from the clutches of a marauding band of blood-foaming zombies after he came-to in an abandoned hospital.
It's as if tribes of miffed Roy Keanes are swarming the city after animal rights activists release infected apes, unleashing a 'rage' virus on an ungrateful nation.
With Jim's occupation as a courier, you might think he's no stranger to anti-social behaviour but even he's taken aback when Selina slashes an infected Mark to death.
She tells him that to stay alive you've got to kill within the blink of an eye - hence the no-questions-asked dispatch of her old ally.
Hooking up with the genial Frank (Brendan Gleeson) and his daughter Hannah (Burns), the foursome - fortified by Pepsi and Maltesers - realise they have to escape the city.
After picking up an army broadcast, they head up the motorway in a London cab to find salvation in Manchester (now there's a novelty).
Boyle has conjured up a compelling gut-churner, strong on images (it's shot on digital video) and displaying a nice balance of gore and gags.
In a stunning opening scene, Jim wanders through a deserted metropolis that Red Ken's congestion charge could only achieve in his wildest dreams.
Upturned double-deckers block the Mall and appeals for survivors are plastered over Eros's monument in Piccadilly Circus.
The first half is a pretty standard - but often inspired - George 'Night Of The Living Dead' Romero-style series of clashes between the survivors and 'the infected'.
However, with the introduction of Ecclestone's army unit a disturbing Darwinian twist is introduced alongside the thrills and the chills.
The earlier lighter moments - including a memorable Supermarket Sweep-style trolley dash - all but disappear as the mood darkens to an infernal gloom.
Writer Alex Garland, who penned The Beach, seamlessly plaits in a horrific moral strand to the already nail-biting simple battle for survival.
Following hot on the heels of My Little Eye, a British horror film to shout (and scream) about.