Just when you think you've seen everything that can be done with that exhausted horror genre, the vampire picture, somebody comes along with a new twist.

A couple of years ago, it was the Russian "balance of terror" thrillers "Night Watch" and "Day Watch." Last holiday season, it was teen vampires in "Twilight."

Now we have the oddest of them all, the dark and demented "Let the Right One In," about blood-craving at a Swedish middle school. Tomas Alfredson's film of John Ajvide Lindvist's novel takes the genre conventions into new and disturbing places.

The vampires may be the least disturbing things about it.

Oskar (Kare Hedebrant) is a lonely 12-year-old who barely copes with being the school bullies' punching bag. He plays with his knife and mutters tough guy threats into the mirror, into the snowy darkness — but never to his tormentors.

Then he meets the mysterious Eli (Lina Leandersson), a haunted 12-year-old with ancient eyes and bare feet.

"Aren't you cold?"

"I guess I've forgotten how," she says. And don't go getting any ideas, she adds. "Just so you know, I can't be your friend."

Oskar lives in the adjoining apartment. He works out a code to tap out messages to Eli. But he also notices the way her windows are covered, the much older man who shares her place and the occasional dabs of blood on her lips.

Bizarre, ritual murders come to their Stockholm suburb. We see how they're carried out. And we see Oskar connect the bloody dots.

"Let the Right One In" is a film of over-illuminated midnight snowscapes, of blonds and barflies, divorced parents and latch-key kids visited by grisly, shocking attacks. The juxtapositions are jarring. Here, in the winter wonderland, Oskar's childish priorities — finding a friend and coping with bullies — collide with the supernatural and budding sexuality. Yes, they only come out at night, but the young leads and the middle-school situations (ever-escalating bullying) ground this in a chilling reality.

"Let the Right One In," in Swedish with English subtitles, builds on the quiet spell cast by falling snow, climaxing in a third act of stunning violence and hysterical cats.

It's hard to remember a vampire movie drenched in more dread than blood, though in this corner of Sweden, there's plenty of both.