Attack the Block

The hairy, luminescent-fanged extra-terrestrials that wreak havoc in “Attack the Block” are exotic and frightening, to be sure. But then, so are the hoodlums defending a South London tenement building against them. People are already afraid to go out after dark in this neighborhood; what difference will a few vicious space monkeys make?

This smartly assembled, effortlessly cool sci-fi comedy — written and directed by Joe Cornish and produced by the “Shaun of the Dead” and “Scott Pilgrim vs. the World” team — makes instant stars out of the charismatic non-professionals who comprise most of the young cast. That’s an especially tricky feat given that the characters start out as contemptible street punks, a roving gang of bat- and chain-wielding muggers under the leadership of Moses (John Boyega). They have personality, though, and a lot of brains hidden behind their swagger.

Given their violent natures, it’s no surprise that their reaction to encountering an alien creature is to beat the crap out of it. But violence begets violence, and soon there are more E.T.’s seeking revenge. The boys find unlikely allies in Sam (Jodie Whittaker), a tough, pretty nurse whom they previously mugged, and in a couple of reluctant stoners played by Luke Treadaway and Nick Frost. Those two are the most overtly comic characters, but everyone’s dialogue is fresh and lively, sometimes so rich in what I assume is real South London slang that it might as well be a foreign language.

If this were a heavy-handed message movie, the alien invasion would force Moses and his crew to realize that they have not been living up to their potential as members of society and to change their felonious ways. That is kind of what happens — but the process is thrilling, raucous, and absurdly entertaining. Few movies this year have been as all-out fun to watch as this one.

B+ (1 hr., 28 min.; R, pervasive harsh profanity, some strong sci-fi violence.)