At last: the mutant alien redneck zombie movie the world has been waiting for. ''Slither" is cheap, disgusting, and ridiculous; it's also smart, very funny, and knowingly in touch with its B-movie roots. The faint of heart should skip it, but if your guilty-pleasure tastes run to such storied horror-comedies as ''Re-Animator" and ''Tremors," here's your cup of extraterrestrial gastropod guts.
Before a meteor lands on the edge of town, not much happens in Wheelsy besides deer season and inbreeding. Mayor Jack MacReady (Gregg Henry) is a blow-dried pottymouth, while police chief Bill Pardy (Nathan Fillion of ''Serenity") pines for his childhood sweetheart, schoolteacher Starla (Elizabeth Banks). Unfortunately, she's married to Grant Grant (Michael Rooker), the macho blowhard who's Wheelsy's leading citizen.
Even more unfortunately, Grant gets too close to a pulsing pile of slime in the woods, and soon he's haunting the deli counter at the supermarket, growling, ''Meat." Say what you will about the man, he does love his wife, even after he transforms into a giant tentacled slime monster. The mayor's convinced it's just Lyme disease; the police aren't so sure and plot their quarry's whereabouts on a map with little squid icons.
Every worthwhile horror movie since ''Alien" has its carefully worked out evolutionary calculus, and ''Slither" is no different. One of Grant's early victims becomes a giant human womb that releases millions of blood-red slugs that fan out across town, leaping into people's mouths and turning them into zombies controlled by the Grant/alien thingie. This means that whenever Starla encounters one of the undead, he or she insists on working out the couple's domestic issues. Can you do couples therapy with a hive mind?
The slug-attack sequences are giddy and terrifying -- drive-in cheese at its creepiest -- and the bathtub scene lives up to its billing on the film's poster. ''Slither" does for taking a good, long soak what ''Jaws" did for swimming in the ocean.
As rousing as it is, the gore's for the diehards. What makes a good horror-comedy work -- as opposed to all the teen dice-and-slice ''product" that clogs up multiplexes -- is sharp performances, sharper timing, and a willingness to admit to the genre's fundamental silliness.
''Slither" has all three. The acting is playful aces all around: Fillion gives good exhausted incredulity, Banks gives good virginal idiocy, and Rooker gives great conflicted monster arrogance even before the aliens get him. The film moves forward with the relentlessness of a low-budget nightmare, pausing every so often to point, giggle, shriek, and run away.
Writer-director James Gunn has been around the block, and ''Slither" is a winking resume of his influences. The town's beer joint is named Henenlotter's in honor of the director of the grindhouse classic ''Basket Case" (1982), while David Cronenberg's 1975 ''They Came From Within" gets a viscous shout-out. Gunn earned his stripes writing scripts for the Z-movie studio Troma, which accounts for the company's president, Lloyd Kaufman, showing up in a cameo as a wino. He also wrote the recent ''Dawn of the Dead" remake, which explains this movie's deep knowledge of zombie behavioral habits (i.e., they never run but can only totter).
Still, it's Gunn's love of the absurd that keeps ''Slither" sailing along its bloody track. After a series of developments that raise the ick factor to jaw-dropping levels, the movie scores the climactic showdown between Starla and what used to be her husband to the couple's favorite song. Who knew that when Air Supply recorded its gloriously sappy 1980 hit ''Every Woman in the World," it would find its true meaning as the expression of the love between a woman and her slug.
Ty Burr can be reached at email@example.com.