Rated R

Sometimes the best defense is a strong offense.

According to “Attack the Block,” that strategy might apply equally to both confronting a mysterious plague of shaggy rabid space raccoons with needle sharp day-glow gnashers and to providing a bracing reprieve to many of the tropey pitfalls big-budget alien invasion flicks have fallen into in the last 20 years.

With this superb debut feature, writer/director Joe Cornish (previously a lesser known British TV comedian and occasional Edgar Wright conspirator) reminds us that despite Hollywood’s frequent insistence that extraterrestrials need a reason to invade us (more often than not, apparently, to blow up our national monuments and poach our stuff), at its root, the word “alien” means simply, foreign or strange. The power of aliens, as a plot device, is embedded in the protagonists’ inability to fathom the depths or dimensions of an indefinite threat.

By marrying this primal fear of the unfamiliar to a decidedly provincial pack of gangstas, thieves and potheads in a London tenement slum, Cornish very effectively constructs a dynamic that is simultaneously aboriginal and thoroughly modern. The kids, who encounter, and summarily murder, an aggressive little beast that meteors down to interrupt their mugging of an innocent young nurse in the streets outside of their apartment tower, struggle to define the experience in terms completely cobbled together with references to movies, video games and cartoons. The nearest any of them seem to have to a legitimate education is a slight preoccupation with the Discovery Channel. “It’s rainin’ Gollums,” one shouts. “You killed Dobby the Elf,” says another. Though perhaps lacking refinement, these kids are in no way stupid. In what seems a sensible idea under such circumstances, they drag the corpse back to their building to figure how much they might get for it on eBay.

As more, and far worse, creatures begin to unaccountably rain down from above, and the boys scatter back to their respective bedrooms, making up excuses to parents and siblings along the way, to snatch up chains, baseball bats, fireworks and naturally, one of their dad’s decorative ninja swords off the wall, there’s a perfect, freewheeling perception that they are definitely about to get in way over their heads, and that they certainly could not care less. Their complete inability to properly qualify the peril in front of them is evenly matched by a wonderfully vigorous enthusiasm for kicking its ass.

The reckless bravado with which these little hoodlums embrace their ignorance is at first quite refreshing in a scary, “Clockwork Orange” sort of way, and is in unmistakable balance with the creatures against which they clash. Throwing up a clear middle finger to the recent enslavement of movie alien design to overzealous, hyper-biological computer renderings, Cornish’s creatures are ingeniously simple. They are blind, battering black ink blots that, even in full view, reveal exactly one detail: teeth. Lots of teeth.

They work as a solid, visceral hazard on screen, lurking the Block’s shadowy hallways, scaling its walls and crashing through its doors, and also as a remarkably underplayed metaphor for the juvenile mindlessness of the central gang. In confronting these inscrutable monsters, the kids are forced, in a number of ways, to recognize their true limitations (the films ‘R’ rating should probably indicate that they won’t all make it out in one piece), face the consequences of their actions (including the mugging that begins the story), and in one of the films most effective turns, learn to accept responsibility for what they’ve done, take action to set things right, and subsequently, grow the hell up.

Cornish, with a miniature budget and a largely amateur cast, has managed what the Big Boys haven’t for quite some time: he’s made a brash, energetic, original little film with great humor, pace, personality, and intelligence. With a scrappy insolence and a growling soundtrack to boot, this movie should probably be called “Attack the Blockbuster.” After this years’ glut of bloated invasion duds (sorry Favreau), it’s safe to proclaim that Cornish wins.