Slither is the equivalent of an emotional workout. It will have you squirming, screaming, jumping, chortling, howling and groaning.
James Gunn, who wrote and directed this sci-fi horror spoof, previously wrote Scooby Doo and Dawn of the Dead, which should give you some idea of the two extremes Slither pursues with such irreverence.
The hick town of Wheelsy is under attack from an alien life form that turns its victims into ravenous zombies.
This extraterrestrial terror invades humans in the form of slugs that slither through the mouth and into the stomach.
It's essentially what happened in David Cronenberg's Rabid three decades ago.
And, like the scientist in Cronenberg's The Fly, the original human host transforms into a hideous creature. In this case, it's Michael Rooker's rich, lecherous Grant Grant, who morphs into a gargantuan squid.
The alien part of Grant wants to mate with the human part's young, nubile wife, Starla (Elizabeth Banks), so it can start a hybrid race -- and so Gunn can have himself a sequel if this one makes a huge profit.
That might just happen because Slither really delivers on the gore, fright and humour levels.
Like those alien children in Village of the Damned or the pod people in Invasion of the Body Snatchers, the zombies are really just cells of Grant Grant.
They all have his thoughts, desires and memories.
To kill them, our heroes must kill Grant -- or the squid creature he has become.
What he's become is a gross-out version of that man-eating plant, Audrey 2, from Roger Corman's Little Shop of Horrors.
The unenviable task of battling the monstrous monster falls to Starla, town sheriff Bill Pardy (Nathan Fillion) and the surprisingly resourceful teenager Kylie Strutemyer (Tania Saulnier).
Pardy is not-so-secretly in love with Starla, so he's really eager to destroy Grant.
Fillion delivers all his lines with droll sarcasm.
What's even funnier is that Fillion's sheriff isn't all that perplexed or dumbfounded by what's happening. It's almost as if there's a chapter on alien invasions in his lawman's handbook.
Banks gets to go from sweet and innocent to a bit of a sexy vixen.
In a film of such ludicrous extremes, Saulnier manages to make all of Kylie's reactions seem grounded in some kind of bizarre reality.
On the other hand, Gregg Henry plays the town mayor as if he's in one of those '50s mutant insect movies. There isn't a hint of subtlety in his performance and that, too, is funny.
Like most sci-fi and horror films, Slither has its agenda.
The fact that the zombies eat until they burst is an obvious comment on America's growing obesity trend.
Though Slither pays homage to dozens of sci-fi and horror flicks, it is most like Tremors and Eight Legged Freaks in tone.
Both those flicks had to wait until DVD to earn the cult status they deserved.
(This film is rated 18-A)
