The good news is that as far as sequels go, 28 Weeks Later is actually a pretty good movie. Not nearly as good as 28 Days Later, the follow-up suffers in some of the same ways the predecessor did. It runs a bit too long, and feels a bit padded out at times. But all things considered, 28 Weeks Later manages to deliver a solid bit a horror entertainment.

Despite the title, 28 Weeks Later starts off during the height of the plague chronicled in the first film. As the film begins, the highly contagious Rage virus that renders its victims mindless, homicidal maniacs is still sweeping through England. A small band of survivors has taken refuge in a barricaded cottage removed from civilization. Among the survivors are Don (Robert Carlyle) and his wife, whose children were away when Rage hit England, and a group of requisite expendables who will only serve as fodder for the impending slaughter. With the introductions and cursory exposition out of the way, the film launches into its first attack, as a horde of the infected swarm down on the cottage and lay waste to most of the inhabitants. Don flees the scene, cowardly refusing to help his wife, as an army of the infected pursues him across the lush green countryside. The whole sequence is an adrenaline-fueled nightmare, and as good as any of the action/horror sequences in 28 Days Later, and it's just the first fifteen minutes of the movie.

Having narrowly escaped the infected, Don drifts down a river in a small boat, left to wrestle with the guilt of what he has done, and what the future will hold. Fast forward to six months later: The Rage virus has run its course, the last of the infected have starved to death, and England is in the process of rebuilding. With the backing of NATO, the U.S. Army now occupies London, where is has set up blockades, defense perimeters, facilitated the clean up of a decimated nation, and begun helping repopulate. Don is part of a small band of survivors that makes up the population of a tiny district that has been deemed safe. Among a group of British citizens arriving to repopulate London are his children, Andy and Tammy. But things quickly turn sour when the children, who want a photograph of their mother, enter into part of the city that is still under quarantine. When they arrive at their former home, Andy finds his mother, half-crazed, living in the attic, where she has been hiding for who knows how long. The problem is that dear old mommy has been infected with Rage, and though she does not show any of the symptoms, she is a carrier of the disease. Once she is brought to a military complex for testing, it is only a matter of time before all hell breaks loose, and the disease once again begins to spread like wildfire.

With what appears to be a bigger budget that the first film, director and co-writer Juan Carlos Fresnadillo, who inherits the reigns of Boyle and writer Alex Garland, delivers a film with a much larger scope. There is more emphasis on action and special effects this time around, which will lead to the inevitable comparisons of Alien and Aliens. And in many ways, 28 Weeks Later does borrow from the Aliens book of sequels. But at the same time, Fresnadillo also seems to have mined the same source as Garland and Boyle. Where 28 Days Later was heavily influenced by George Romero's Night of the Living Dead, Dawn of the Dead and Day of the Dead, Weeks draws deep from a more obscure Romero film, the under-appreciated 1973 gem The Crazies. Of all the films fans that critics will compare 28 Weeks Later to, The Crazies is second only to Aliens in the films it mirrors.

Fresnadillo proved himself capable of stylish, kinetic direction with his film Intacto, and with 28 Weeks Later he manages to take things to a higher level. When the film is actually in motion, and not being slowed down by expository nonsense, it moves at a quick pace, with a tension that can be almost unrelenting. As the virus begins to spread and the infected begin to swarm, the second and third act of the film turn into a frenzy of grim violence. In one of the film's most brutal sequences, rooftop snipers systematically target the infected as they run through the streets. But as it becomes clear that the situation is getting out of control, they receive orders to target anyone on the ground, regardless of whether or not they are infected.

Jeremy Renner co-stars as an Army sniper, who as part of the U.S. forces in England are there to facilitate the rebuilding of the United Kingdom. The inability of the United States to stabilize the region, and the massive destruction they reign down on both the infected and innocent civilians serves as not-so subtle metaphor of the war in Iraq. Not since a radioactive dinosaur name Godzilla leveled Tokyo has there been a more condemning metaphorical representation of the U.S. military in a genre film. In fact, there's not even really any metaphor or allegory in 28 Weeks Later, the U.S. military is the film is just that, the U.S. military. There is no clever disguising of what is going on, or what is being said. Fresnadillo, to his credit, does little to mask the larger picture he is painting beneath the canvas of a horror film.

The film's biggest weaknesses are a lack of clearly defined protagonist. Carlyle starts out as the closest thing to a hero, but he turns out to be anything but. Renner emerges in the second act as more of the protagonist than anyone else, and he is certainly far more likeable and sympathetic than Carlyle's character. But there is never any individual character for the audience to latch on to as the savior of the day. The film's other major flaw is the introduction of an infected character that feels too much like someone trying to create a new horror icon. Without giving away too much of the story, there are moments with this character that feel like a pathetic attempt to mirror what Romero has managed to successfully do with key zombies in his film, but in this film it amounts to nothing more than a failure that comes across as contrived coincidences.

28 Weeks Later does not feel like the groundbreaking reinvention that 28 Days Later was, but there is no way that it could ever be that. At the same time, it makes real the promise that Grindhouse failed to deliver, succeeding as fairly well-paced, violent, gore-splattered entry that should make true horror fans happy.