CRY_WOLF

***

Sharp and sharp-toothed.

Running time: 90 minutes. Rated PG-13 (violence, disturbing images, profanity, sexuality, a drug reference). At the 84th Street, the Magic Johnson, the E-Walk, others.

WHICH is scarier: a ma niac in an orange ski mask wielding a hunting knife – or Jon Bon Jovi as a journalism teacher?

“Cry_Wolf” gives us both, and though Bon Jovi is livin’ on a prayer if he thinks he’s an actor, the movie is a find. It was buried by its makers, who didn’t screen it for critics. But it’s alive! Instead of gore, it has a crafty Agatha Christie-style script and a smart lead performance by Lindy Booth, who walks away with the movie and a bright future.

Booth is the impish redhead Dodger (“My mother is a Dickens scholar”), a prep school student who takes a fancy to Brit transfer Owen. She invites him to join the scary game she plays with other students at midnight. One kid plays wolf and lies about it; the others guess who it is.

Meanwhile, a girl has been shot to death in the nearby woods, but she was a townie. So who cares?

Owen suggests playing wolf with the entire school. He sends a mass e-mail telling students that the dead girl was merely the latest victim of a serial killer, “the wolf,” who wears an orange ski mask.

No one falls for the hoax, but soon Owen is getting sick IM’s from someone posing as the wolf. A student goes missing, suggesting he’s either the first victim or the wolf. And a hunting knife tumbles out of Owen’s backpack right in front of a suspicious teacher (Bon Jovi).

The movie consistently keeps us guessing, right up to its twisty, satisfying finish. The inanities you expect from teen stabathons, like the faux-hip dialogue, are absent. Most entries in the genre would fall apart if anyone had a cellphone, but this movie uses real-life technology to rev up the suspense. At one point, a cellphone is used so cleverly to update an old gag that the idea is bound to turn up in the next 50 slasher flicks.