Let’s cut to the chase: this is the coolest, most intelligent action movie of the year, indeed of several years. Sure, J.J. Abrams’ “Star Trek” was great, but what made it work was that in effect it was as comfortable as an old shoe—wonderfully crafted and smart, to be sure, but still pleasantly familiar. “District 9,” on the other hand, has edge and even rage. It surprises and challenges as it turns “Close Encounters” on its head.

But in a way it’s a throwback, too—to the science-fiction of the fifties that didn’t just try to entertain in the juvenile fashion of “Star Wars”and its endless progeny, but said something about social issues too (the way Roddenberry’s original did), however heavy-handedly. The picture is spellbinding but thought-provoking as well, which is a nice change from actioners that are so obsessed with wowing you that they resolutely avoid any ideas at all. It’s visually striking and provides an adrenaline rush, but it also has a brain.

The premise is that a huge alien ship appeared over Johannesburg some two decades ago and simply stalled there in the sky. When the South African government finally sent an expeditionary force to enter the vessel, they found hundred of thousands of ill, starving extraterrestrials—human-sized but insect-like, speaking in a language of clicks and gurgles. The response was to transport the creatures to the planet’s surface, treat and feed them, and integrate them into the population as resident aliens, even giving them “human” names just as officials did with immigrants at Staten Island in the nineteenth century.

Now, after twenty years, the ever-growing alien population, none too affectionately called prawns, are crammed into a run-down township called District 9, and hostility toward their habitual scavenging and theft has grown to uncontrollable levels among the locals. As a result the government has decided to relocate the aliens to a facility away from the city, and has handed responsibility for the operation over to a powerful private firm called Multi-National United. The employee assigned to oversee it is Wikus van der Merwe (Sharlto Copley), an earnest, ferret-like mid-level bureaucrat whose can-do attitude masks his insecurity. Eviction proceedings prove difficult, however, especially because one of the aliens, Christopher Johnson (Jason Cope, who also “plays” the other full-sized creatures rendered visually by great CGI effects), is engaged in a project designed to restart their ship and return home. Unfortunately, that requires collecting a sticky substance from bits of surviving alien technology that will allow Christopher and his little son to ascend to the ship in a ramshackle craft, but the goo also has a peculiar effect on any human who comes into contact with it. And meanwhile other MNU employees are busily working to gain control over the advanced alien weaponry, which can be accessed and fired only by someone with the proper DNA.

It wouldn’t be fair to reveal much more than this about the clever, intricate script by Terri Tatchell and director Neill Blomkamp (for a hint you might check out Val Guest’s 1956 sci-fi classic “The Creeping Unknown,” aka “The Quatermass Xperiment”), but suffice it to say that they employ the complications to raise issues of what it really means to be “humane” in terms of treatment of “others,” whatever their origin. But that doesn’t mean that the movie is preachy. Blomkamp inserts the message into a picture that’s more vibrant and exciting than all this year’s comic book and video game adaptations rolled up together. His use of a gritty, cinema-verite style (courtesy of Trent Opaloch’s cinematography)—framed partially as a documentary, punctuated by phony news footage and kept propulsive by Julian Clarke’s rapid-fire editing—insures that you’ll be swept along by the sheer bravado of the storytelling. And though there’s no lack of exposed viscera, burnt-out corpses and exploding bodies, the gore never becomes simply repulsive. The CGI effects are astonishingly good—as one might expect from the New Zealand specialists who made producer Peter Jackson’s “Lord of the Rings” cycle so visually remarkable—and all told, the movie moves like a roller-coaster ride as exhilarating as it is darkly disturbing.

There’s one other element of “District 9” that’s key to its success—the performance of Copley, who’s amazingly good as put-upon Wikus, the only human figure of much consequence here. The character takes a long, event-packed journey from harried, impulsive, ambitious, but deliberately oblivious underling to…well, we’ll let you find out for yourself what he winds up as; and Copley is dead on every step of the way, making you sympathize with the fellow even when he’s acting most like a frightened rodent. Cope’s contribution shouldn’t be underestimated though you never see what he actually looks like; he’s an important to this film as Andy Serkis was to “The Return of the King” and “The Two Towers,” and equally effective. And David James is appropriately brutish as the leader of MNU’s private mercenary army, who’d rather kill than talk.

But it’s Copley who carries the film on-screen. He and Blomkamp are the reasons that “District 9” isn’t just the best action movie of the year, but one of the best films of the year, period. It’s so good you’re thankful that the adaptation of the video-game “Halo” that Jackson originally hired Blomkamp to direct fell through, making way for this picture instead.