If it's Doomsday, it must be London. Where famished, flesh-eating zombies, infected with human rabies called the Rage virus, haven't eaten in months.

28 Weeks Later . . ., sequel to that cannibals' rave 28 Days Later . . ., hits the ground running, tearing through the English countryside, believed to be depopulated and virus-free (we know better), back to London. There, under the auspices of U.S. military and medical forces who pronounce that everything is under control (in other words: "Mission: Accomplished"), evacuees return to the city.

Two are children. Andy and Tammy (Mackintosh Muggleton and Imogen Poots) were on holiday in Spain when the Rage rocked the U.K. When they are reunited with their father (shifty-eyed Robert Carlyle), he tells them that Mother (Catherine McCormack) is dead. Feeling incomplete without even a photo to remember her by, the youths slip past security and return to their home where they find Mom is one of the undead and Dad is a liar.

I don't know what's more frightening, the psychological terror of knowing your mother wants to devour you, or the physical terror of knowing she can. I do know that 28 Weeks Later . . . holds the audience captive and unusually vulnerable to psycho- and viscero-terror.

In other words, Juan Carlos Fresnadillo's sequel to Danny Boyle's 2003 sleeper hit is a bloody, button-pushing shot of adrenaline. To the original's parable of an unchecked virus, with its intimations of Ebola and AIDS, Fresnadillo overlays a political allegory of an American military occupation gone wrong, with its chilling references to Iraq.

In the panic where no one has the time to make a distinction between a zombie and an innocent, not all the Americans are of the shoot-first, ask-questions-later variety. There is a sensitive doctor (Rose Byrne), who makes an important discovery about the children's mother and becomes a maternal surrogate for Andy and Tammy. And there is a sniper (Jeremy Renner), who resists his commander's orders.

Driving the film is cinematographer Enrique Chediak's sprinting camera, darting left, then right, looking over its shoulder to escape the ravenous horde. (His kinetic camera has the collateral benefit of not focusing too long on the gore.) And John Murphy's electronic score turbocharges the action, which does things to the nervous system that deep breathing cannot calm.

StartTextDirected by Juan Carlos Fresnadillo, written by Rowan Joffe, Fresnadillo, Jesus Olmo and E.L. Lavigne, photography by Enrique Chediak, distributed by Fox Atomic.

Running time: 1 hour, 39 mins.

Don. . . Robert Carlyle

Alice. . . Catherine McCormack

Andy. . . Mackintosh Muggleton

Tammy. . . Imogen Poots

Scarlet. . . Rose Byrne

Parent's guide: R (violence, profanity, gore, sexuality)

Playing at: area theatersEndText