Premiering at Sundance 2014, Cooties takes place in the heartland, U.S.A.  town of Fort Chicken; the film’s opening montage paraphrases the adage about how you never want to see the sausage made, as a poultry nugget oozing with unclean effluvia comes off the line at the local poultry processing plant and directly to the local grade school, where it’s served up piping hot and appalling. And as Clint (Elijah Wood) – who once left Fort Chicken for New York but is back, reduced to substitute teaching and living with mom while he works on his novel about a haunted boat – reports to the local middle school for his first day subbing, he’s picked the worst possible day to return to his old school; that tainted nugget unleashes a virus that turns any pre-pubescent human into a flesh-eating, murder-crazed mindless machine of destruction.

Cooties feels awfully like a hook in search of a script at times – I can picture some aggrieved hard-core horror fan howling “But where does the virus come from? Wherrrrre?” in their parent’s basement, forlorn in a search for story logic and exposition.  Written by Leigh Whannell (who kicked off the Saw franchise) and Glee co-creator Ian Brennan, Cooties may not be especially well-crafted, but it’s also extraordinary clever and packed with an ace cast, from Wood’s accidental hero, Rain Wilson as a macho gym teacher, Alison Pill as a teacher who dates Wilson but remembers Clint, as well as  Whannell himself, Jack McBrayer and Nasim Perdad cast as other teachers forced to fight, flee and/or freak out, with personal conflicts and idiosyncrasies not just popping up throughout the action but also affecting it. (Jorge Garcia gets laughs at a shroom-loving security guard, but the film fails to make ideal use of him; pity.)

And as pitches go, Cooties has a great one, full of chances to have comedy and action with the one not undercutting or overwhelming the other. Kudos also have to go to Cooper Roth, whose bratty student Patriot (“I was born on 9/11, and when I get 18 I’m enlisting to kick some towelhead ass!”) winds up being a very convincing hissing, snarling murder-monster. Directors Jonathan Milott and Cary Murnion, making their feature debut, keep things slick and swift and clever, and the sense of threat is always credible even as our poor educators suit up with makeshift weapons to get out of the school. The stuntwork and acting by the post-infection kids — short, savage and slaughterous — is great, and when you see a little kid get knocked flat on back by an adult with a shovel, the transgression fuels the giggles.

And yet, once Cooties unbottles itself and escapes the school, a lot of the fizz goes out of it; the final desperate rush into the night punctures the sealed envelope of comedy and carnage the film created for itself in the school. At the same time, the Sundance audience erupted in laughter when an audience member identified themselves as a teacher during the Q & A and noted that the film was “very cathartic.”  And the FX and make-up aren’t just top-notch; they’re also used in funny, inventive ways that are also true to the film. A gory variation on a familiar schoolroom torment early on is as funny as it is sick, and a mark of disturbed geniuses at work, Cooties is a film where I’m slightly dismayed by its minor failings and slow spots primarily because you can see where it had greatness, not mere blood-soaked goodness, within its virus-ridden clawing grasp. (Perhaps it’ll get a re-cut before Liongate, who purchased it, release it –at the same time, I think it needs mild fine-tuning, not a Harvey Weinstein blood-on-the-walls vivisection.)  Still, it’s hard to argue with it’s – ahem – infectious flavor of horror-comedy.