Four years after Danny Boyle raised the undead with his bloodthirsty thriller 28 Days Later, acclaimed Spanish director Juan Carlos Fresnadillo sinks his teeth into the nerve-wracking, adrenaline-pumped sequel.

In many respects, the follow-up is a superior beast, set once again in an eerie, deserted vision of futuristic London; grey, cold, foreboding.

Explosions of graphic violence are shocking and set our hearts racing.

The 18 certificate is well deserved, a number of expertly edited action sequences in 28 Weeks Later are exquisitely intense, shredding even the steeliest nerves as the dreaded rage virus returns to mainland Britain with a vengeance.

Fresnadillo expertly sustains the choking tension right up to the closing frames, surpassing the original picture, which lost its way badly in the overwrought final act.

A white-knuckle prologue sets the scene with devastating power, holed up with a group of the uninfected including Don (Robert Carlyle) and his wife Alice (Catherine McCormack), who have barricaded themselves in a house, while carriers of the virus prowl outside.

There are no survivors. It's just us in here and them out there,'' says Don, grateful that his two children, 12-year-old son Andy (Mackintosh Muggleton) and his older sister Tammy (Imogen Poots), are abroad, safe from harm.

Sadly, the people in the house are in very grave danger.

Six months later, after the virus has ravaged the country and blood-crazed carriers are presumed to have died from starvation, NATO forces led by the US army are drafted in to begin rebuilding London.

To that end, hard-nosed General Stone (Idris Elba) and his troops establish District One, a quarantined zone on the Isle of Dogs.

Military doctor Scarlet (Rose Byrne), who oversees detailed medical checks of all new arrivals, is shocked to see Andy and Tammy among the latest influx: No one told me we're now admitting children,'' she tells a colleague.

The youngsters join the rapidly expanding District One community, under constant scrutiny from gun-toting snipers including Special Forces sergeant Doyle (Jeremy Renner).

Alas, a carrier of the infection manages to infiltrate the enclave and unleashes the plague, with horrific consequences.

Abandon selective targeting. Shoot everything. We've lost control! commands General Stone as his snipers open fire.

The children seek refuge with Scarlet, but the chances of survival are slim, as Doyle - who disobeys orders and abandons his post - explains military protocol.

Step 3: Extermination,'' he tells them. They won't stop until you're all dead,'' 28 Weeks Later confirms Fresnadillo as one of the most talented European filmmakers working today, shot largely on hand-held cameras to ensure freedom of movement during chases that afford little respite from the gore or the nail-biting suspense.

Muggleton and Poots are both excellent, completely devoid of the cuteness that afflicts most young actors, caught in the midst of bravura action set pieces like the bombing of the capital to eradicate the zombies.

A showdown between a rampaging mob of the infected and a helicopter piloted by Doyle's pal Flynn (Harold Perrineau) is sick, twisted and hysterical.

Equally amusing is the coda, wedging a tongue in the film's battered and bruised cheek.