As the horror-comedy Slither opens, a small-town cop passes the time by clocking a whippoorwill with his radar gun. (It flies at 27 mph, which is a little less than his partner estimated.) Meanwhile, an asteroid comes careening down from the heavens, traveling at a speed that would surely amaze a bored deputy with nothing better to do than to clock whippoorwills. But poof, the blazing fireball lands undetected in the woods behind his cruiser. Right from the start, the film toys knowingly with the audience's expectations, and the surprises keep coming until the end, when another brilliant piece of misdirection postpones the big payoff to agonizing effect. Writer-director James Gunn, who scripted the recent Dawn Of The Dead remake, clearly understands horror movies inside and out: In the tradition of knock-off pleasures like Tremors, Dead/Alive, and Shawn Of The Dead, Slither goofs on the genre with sneaky wit and an infectious will to entertain.
Paced like a whipcrack, the film wastes little time in establishing the single Alien-like being that quickly turns a Southern hick town into a zombie apocalypse. While wandering drunkenly through the woods after a fight with his pretty young wife Elizabeth Banks, Michael Rooker comes upon a seemingly harmless slug creeping along the forest floor. But when he leans closer to investigate, the creature shoots him in the gut with a projectile, which imbeds in his brainstem and controls his increasingly bizarre behavior. First it's just an insatiable craving for meat, but as his body begins to resemble a giant squid (or, as one character colorfully puts it, "something that fell off my dick during the war"), a plot emerges to take over the town with more creepy-crawlies. Standing in the way is no-nonsense police chief Nathan Fillion, whose unflappable nature is put to the test.
Though it occasionally dips too deep into a well of redneck humor, Slither cleverly exploits the nervous laughter that fills a theater whenever a horror movie gets too frightening to bear. And one of the key reasons it's so funny is that it is frightening: Once Rooker transforms into a grotesque mutation, and his army of slugs make a beeline into every orifice they can find, the film generates one skin-crawling sequence after another. (The scads of phallic and vaginal imagery alone hint at some unspeakably creepy subtext.) With a game cast of C-list actors—led by Serenity's Fillion, who seems to have the most fun in the stickiest situations—Slither may look like the undercard to a drive-in double feature, but it easily outclasses the solemn shockers that the studios crank out every week. And it's scarier, too.