Television veteran Danny Boyle began his filmmaking career with the double bang of Shallow Grave and Trainspotting, but continued it with a whimper (The Beach, the disastrous A Life Less Ordinary, the aborted Alien Love Triangle). Boyle's latest film, 28 Days Later, follows a similar pattern, getting off to a terrifying start before devolving into gory bloodshed and ham-fisted allegory. The script came from Alex Garland, who wrote the novel on which The Beach was based, and while those two films are miles apart in terms of budgets and genres, they have surprisingly similar themes. Each dissects a makeshift society that's set apart from the rest of civilization, and that crumbles due to the cruelty inherent in human nature. In The Beach, the society in question was a utopian island community that rapidly became a dystopian nightmare. In 28 Days Later, it's a group of survivors of a horrific virus that devastates the U.K., and possibly the rest of the world. After Cillian Murphy wakes up in a hospital, he ventures out into an eerily still London in which a handful of uninfected survivors strive to stay one step ahead of zombie-like disease carriers. Murphy travels through the wreckage with tough-talking Naomie Harris before joining forces with a girl and her gentle father (a touching Brendan Gleeson). Later does a lot of things right, which makes its third-act missteps even more frustrating. Cinematographer Anthony Dod Mantle, who recently shot Lars von Trier's Dogville, makes inspired use of digital video, using its blurry, voyeuristic intimacy to convey the disorienting horror of a world where death and disease hover like a ghostly fog. The film similarly concocts a terrifying new subset of zombies that are sleeker, faster, and more ferociously primal than their often lumbering ancestors. Boyle and Garland wisely use their frightening monsters sparingly, which allows them to retain their shock and novelty: The infected never hang around long enough for the audience to get used to them. But while Later maintains the same sort of restraint for much of its duration, it casts that restraint aside during a bloody, over-the-top final act that diminishes the film's scary poignancy. Like his makeshift societies, Garland's tantalizing set-ups tend to unravel in unsatisfying ways.