PARK CITY - Ten years to the day after "Saw" made its midnight premiere at the Egyptian Theater as part of Sundance's midnight lineup, co-writer Leigh Whannell showed up with a whole different team of collaborators to premiere "Cooties," a horror-comedy that manages the very difficult trick of fulfilling both halves of that equation with equal skill.

Directed by Jonathan Milott and Cary Murnion (collectively known as "Honest" when they co-direct) and written by Ian Brennan & Leigh Whannell, "Cooties" tells the story of a rapdily-spreading infection that turns all the kids at an elementary school into rabid little flesh-eating monsters, and what happens on the day the situation spins out of control. Clint (Elijah Wood) is a substitute who actually went to that same elementary school when he was a kid. He's only teaching for a little while as he works on his first novel, "Keel Them All," a story about a haunted boat. He's delighted to see that one of his childhood friends Lucy (Allison Pill) is also teaching at the school, but slightly less delighted when he meets her current boyfriend, PE coach Wade (Rainn Wilson). For the first twenty minutes or so, "Cooties" is basically just a comedy about a guy who isn't where he wants to be in his life trying to cope with returning to his elementary school, but in a new role, while also trying to navigate the bizarre social hierarchy of the teachers who are there full-time.

Actually, that's not totally true. The film's opening scene and opening titles take place at a chicken processing plant, and I have to say, it's one of the most nauseating openings to a film I've seen in a while. We watch as we got from a live diseased chicken to a disturbing chicken nugget served to an elementary school girl over the course of the title sequence, and we see very filthy step along the way, right up to the moment she bites into it and some nasty grey stuff oozes out.

The next time we see that little girl is in Clint's classroom, and once she goes nuts and bites the class bully, a chain reaction begins. We watch these two very different stories unfold until they finally collide, at which point "Cooties" kicks into overdrive, throwing gore and jokes at you almost non-stop. I say "almost" because there are a few great character beats where they actually take a step back to acknowledge how transgressive some of what we're watching really is. After all, once people turn into zombies and start eating other people, you know what you have to do to stop them, right?

There is a real sense of crossing a moral boundary when the film makes that jump, and one of the most self-assured moments in the film happens after Wade finally bashes one kid's head in with a fire extinguisher. To the credit of all involved, it's not just treated as another laugh. There is a feeling immediately that something big has happened, and it obviously shakes Wade deeply. By finding the right moments to punctuate in small, simple, human ways, "Cooties" buys itself room to be more outrageous in other moments, and it also makes it okay when things go totally bananas in the third act.

Wood, Pill, and Wilson all do sterling work in the leads, and the romantic triangle between the three of them would work perfectly well as a comedy by itself, especially since Wade sees right through Clint's cheery facade. Clint is starting to realize that he may never actually finish a book, and it's hard for him to admit. He likes the way Lucy looks at him when he tells he stories about working in New York and how hard he's working on his novel, and Wade feels threatened by him. I think Wilson is a singular comic performer, and his work here and in "Super" makes me think he's one of those guys who attacks a scene from a completely unique place. It would be easy to play Wade as a one-note jerk, but that's not what he does with the role at all. Likewise, Wood has proven himself a huge fan of genre films, and he makes choices with how he plays Clint that don't play into our typical idea of what a hero in one of these films looks like.

Nasim Pedrad, Jack McBrayer, and Jorge Garcia all get chances to play some outrageous notes in their characters, and they're good at etching in the details of these people quickly. Co-writers Brennan and Whannell are also both in the movie, and I think Brennan's principal character is very funny and very weird. Whannell's character, however, emerges as one of the strangest supporting characters in any film I've seen recently, a hilarious and jet-black-horrible character who wants desperately to figure out how to see normal even though, as we learn over the course of the film, normal is the one thing he absolutely is not.

My one real issue with the film is that they spend almost no time establishing any of the kids, even the two who end up surviving. There are some funny beats early on with the kids, and they're involved in some of the film's big moments, but for the most part, the kids get pushed to the background very quickly. They become the faceless monsters, and while there are some very funny gore gags and some funny visual moments, it feels like the film could have done more to balance which characters we get to know.

Still, it's a small complaint, and when "Cooties" is really working, it's tremendous fun. I suspect some distributor is going to have a field day cutting together a campaign for this one, and when they do, I highly recommend you give yourself a circle-circle-dot-dot and head out to catch "Cooties" for yourself.