It's Guy Fawkes Day, with fireworks going off in the background. A young nurse, Sam (Jodie Whittaker), is walking home from work when she's surrounded by five masked, menacing figures. They pull a knife on her, demanding her phone, her money, and her ring, when suddenly there's an explosion in the background. A car window shatters, and Sam uses this distraction to run away.

The leader of the gang, Moses (John Boyega), goes to explore the car (or rather, to find out if there's something worth stealing in it), and is jumped by what looks like a feral gremlin monkey. (The dialogue in the background, after Moses knifes it in the leg: "What the fuck was that?" "Some orangutan type thing . . . I'm not even lyin bruv." "Hey, it's breezin', man. It looked like Dobby the house elf." "Moses got shanked by a Dobby!") The gang, led by Moses, chases and kills it, and then does what any rational group would, when faced with a dead creature of unknown origins—treats its carcass like a trophy, trying to figure out how much money they can make through eBay and the press.

This is the opening of Attack the Block, British comedian Joe Cornish's first feature film, released earlier this summer and now out on DVD. It spans the course of one night, when aliens that bear a marked resemblance to overgrown gorillas invade the Earth. Unfortunately for the aliens, they have chosen the exact wrong place to start their invasion, the South London Wyndham House council flats where Moses and his friends live.

The aliens in this movie are menacing enough when they are chasing and killing humans, but nothing especially memorable. And for all that they are interstellar space travelers, they seem much more primitive than humans. The first alien that landed, which Moses and his friends killed, was a female. It released hormones that summoned hundreds of others, all males of the species, bigger and darker and with much sharper teeth. This second wave of aliens has no eyes or ears, no specialized tools, no spaceships (they traveled through space in individual cocoons), and seemingly no desires other than to mate and kill.

But the simplicity and primitiveness of the aliens doesn't detract from this movie, because what matters here is not the threat so much as the group's reaction to it, how the individuals interact, how their personalities and abilities change and are developed when they band together. And this is where the movie shines, with its exhilarating and nerve-wracking action scenes, witty dialogue, and satisfying characterizations.

Moses and his friends are unapologetic thugs, but they're still kids. They exasperatedly obey their parents when they demand that they walk the dog, taking it with them to chase down aliens; kiss their grandma on the cheek and promise that they'll be back by ten and that no, they're not up to any trouble, honest. They rob and terrorize Sam, and then a few scenes later they're chastising her for swearing too much and becoming offended by her desire to leave their neighborhood, because what's wrong with it? They show an infectious glee when they look out the window and find the second wave of aliens landing, and one of my favorite scenes in the movie comes immediately after, when they're gathering assorted weapons from their apartments (while assuring their families that they'll be back soon, they're just going out to play football), and racing down the stairs and to the park to face the aliens with naive, irrepressible enthusiasm. And then they discover that these aliens are much larger and more deadly than the first, and decide, in the words of Biggz (Simon Howard), that "Right now, I feel like going home, locking my door and playing FIFA."

Of course, by then, it is much too late.

At the core of the movie is Moses, the one who initially terrorized Sam with his knife, slowly realizing that he has brought the aliens here, and so is largely responsible for the resulting injuries and deaths. Brilliantly played by John Boyega, Moses expresses as much with his eyes and body as with his words, of which he seems to utter less than any other character. The crucial turning point of the movie is when he decides to stop running and hiding from the aliens, and leaves the sanctuary of Ron's weed room—on the nineteenth floor, the most secure place in their building, where the survivors have retreated—to "finish what [he] started" and save the Block. His emotional arc is straightforward and familiar, adhering as it does to the Western ideal of the hero's journey, but he lends it a heart and gravitas that nevertheless makes it compelling and memorable.

Another aspect of the film that is remarkable is how it takes a setting—a London council estate, similar to housing projects in the US—that is usually portrayed as dull and unpleasant and banal, and gives it a sort of stark, neglected, futuristic beauty, the type that belongs in a dystopian science fiction novel. There's the basement with its endless, geometric rows of lights and shuttered parking/storage spaces where the gang faces off with Hi-Hatz, the local drug kingpin, after they accidentally hit his car. The curves and angles of the stairs and ramps in the chase scenes. The fluorescent lighting in the hallways filled with smoke, and the UV light over the rows of pot plants in Ron's weed room, evoking the claustrophobic feel of space stations.

It is a setting that serves to reinforce the reality that Moses and his gang live in, where the authority figures, from Hi-Hatz and his men to the police, are more likely to murder or imprison them than protect them. When Sam wants to call the hospital after Pest (played by Alex Esmail, he is the crazy, loudmouthed member of the group, the foil to silent, stoic Moses) has been injured by one of the aliens, Moses refuses to let her, saying, "This is the block. We take care of things our own way. Get me?"

And yet, despite the claustrophobic, futuristic feel of the setting and setup, evoking dystopian scifi movies such as A Clockwork Orange (1971), the storyline is pure Hollywood adventure flick. The film doesn't pull any punches when showing the consequences of an alien invasion, and some of the original gang end up dead. Yet there is no dwelling on the futility of life, the ease and arbitrariness by which it can be taken away. Rather, the violent deaths serve to bring the remaining survivors together. There is a stark, neglected beauty to the Block, and underneath the consciously-built tough exterior, a sweetness and resilience to its residents. The violent deaths, and the reactions to them, serve to highlight just why the Block, and the people in it, are worth defending.

Attack the Block is a low budget British film with, at its heart, a Hollywood blockbuster storyline about a group of people helping each other overcome an alien threat, and in the process becoming heroes. This storyline is transposed to a very non-Hollywood setting and group of people, juvenile delinquents living in a British council estate, and filmed with a stark, dystopian aesthetic. The film's clever script, unexpected cinematography, refusal to make simplistic moral judgments and gloss over all consequences, and most of all, the sheer, unflagging energy that propels the viewer from scene to scene, makes it entertaining and satisfying in a way that few Hollywood movies are.

Guria King lives in the US (and occasionally in other places). Sometimes she writes; most often she procrastinates. For more, follow her on Twitter.