rated R

In the predecessor to this film, “28 Days Later,” writer/director Danny Boyle (“Trainspotting”) took a modest budget and a great cast and turned the admittedly tired, shambling zombie genre inside out. He rewrote the mythos to reflect more modern fears while still holding on to many zombie conventions, such as claustrophobia, panic and inescapable threats stalking in the dark. But the conventions he changed made an immediate impact. First of all, the zombies were not zombies in a strict sense of the word. The film tapped into our growing fear of pandemic diseases by making the antagonists victims of an unnatural, engineered virus. This disease would drive “the infected” into twitching and unthinkably violent rages. Very zombirific. And if that weren’t bad enough, these monsters were fast—real fast. They always ran at top speed, screaming incoherently and retching out virulent tarry black goo, instantly infecting everything they touched (or bit or tore at or sneezed on). Filmed with a shaky, handheld closeness, it put audiences directly into the melee and scared the living wits out of millions of people. This movie could be cited as one of a few very popular and lucrative projects, along with the remake of Romero’s “Dawn of the Dead” and the “Resident Evil” franchise, which have re-animated the living-dead genre. (Pardon the pun.)

While the original film thrilled necrophiles of the world, there may be a downside, and “28 Weeks Later” serves as a sad example. Most of the hallmarks we’ve come to recognize in our favorite underground zombie pictures, such as small sets, low lighting and intimate casts, may well be functions of their infamously low budgets. Rarely do these films secure the finances necessary to actually present the full bore of a true worldwide dead-have-risen type apocalypse. The first film never revealed the full scale of the zombie disaster. It implied, completely by omission, that this infection had possibly decimated our planet’s population.

Now, dragged into the harsh light of the mainstream—with crates of cash, a new director, Juan Carlos Fresnadillo, and a small army of writers—“28 Weeks Later” informs instead that the scope of the epidemic was contained to London and its immediate suburbs. We see extensive new shots of ghost town London with all of its recognizable landmarks, but its huge empty spaces are completely devoid of human activity. As impressive as these images may be, the film manages to expand the perspective of what’s onscreen while simultaneously shrinking the scope of the audience’s perception. After the inevitable resurgence of the infection, the story essentially resets itself back to square one, collapsing into a series of running, screaming, biting scenes on big city streets that they couldn’t afford to shoot in the first go-round. It’s both a treat and a cheat.

In a further attempt to tap into contemporary fears, the role of the military is significantly expanded with the introduction of an unsettlingly familiar U.S. security force. With all manner of helicopters, humvees, sniper rifles and firebombs to play with, we can clearly expect the scale of zombie devastation to take on whole new levels. In one of the movie’s most troubling scenes, rooftop snipers lose control of a chaotic and bloody situation and are ordered to target “everyone” on the ground, infected or otherwise. As soldiers mow down civilians in the streets, the presence of the U.S. Army actually eclipses the infected as the film’s main threat.

The cast here gives it all they’ve got, and they are noticeably more seasoned than those in the first movie. Catherine McCormack (“Braveheart,” “Dancing at Lughnasa”) is appropriately pensive as the know-it-all doctor fighting to convince her military higher-ups that a cure might be at hand. Robert Carlyle (“Trainspotting,” “Full Monte”) is given a few believably emotional scenes in the first act as a flawed family man trying to reconnect with his kids after abandoning their mother to the hands (and teeth) of the drooling nasties. But any degree of gravity that might be established at the forefront is immediately squandered when, having set the bar fairly high, we’re soon forced to re-accept running, cowering and screaming as emotions.

As low budget as it was, the first movie took us on a journey. As high-minded as the new film tries to be, the journey is absent. It starts and ends in London, a few blocks to the east. Big deal. If there’s a lesson to be learned from a living-dead picture, it may simply be that some things are better left underground.