Tense and taut, this low-budget gem that's been making the festival rounds since Sundance 2005 unreels with smooth pace and unexpected grace notes, both visually and by its two leads-a little-known American actor and an award-winning 17-year-old Nova Scotian actress who keep you riveted to two fiendishly smart, endlessly fascinating and utterly despicable characters. Hard Candy is like a game of Russian-roulette chess.

Jeff Kohlver (Patrick Wilson), a.k.a. his nom de Net, Lensman319, is a slick, 32-year-old fashion photographer with romantic stubble and glasses that make him look sensitive-just the dream date for a smart, 14-year-old misfit with pixie hair who finds boys her own age uninteresting and uninterested. As Thongrrrrrl14, eighth-grader Hayley Stark (Ellen Page) agrees to meet him at a coffee bar. She's awkward and embarrassed (this sophisticated older man is interested in her), and after some almost innocent flirting, she persuades him to invite her to his house. On the elevator to the rooftop parking garage, Hayley's face is a mixture of doubt and adventure-and something odd, something more. For anyone who's seen The Professional, this is the moment you begin to think that Page is going out-Portman Natalie Portman.

Once at his pad, Hayley is the self-conscious faux sophisticate for whom "carpe diem" isn't enough-she wants, she says proudly, to "carpe omnium," take it all. Jeff dutifully plays the sad romantic for her, a heartbroken poet-photographer who bravely soldiers on. It's a sharply played cat-and-mouse game of seduction-as sick as it is slick, with a practiced pedophile and a tragically deluded girl.

One roofie later, the tables are not only turned, they're turned over. Jeff is tied up, and Hayley is in charge. She's not going to kill him-she's going to castrate him. What follows-through physical struggle, psychological torture and dialectic debate-is a back-and-forth peeling of layers of apparent truths and shifting identities. "I'm a decent guy-ask anyone!" Jeff pleads. And anyone would say he is, because they don't know him. But as accusations mount, and the helpless Jeff protests his innocence, we're craftily drawn to sympathize with this man who behaved questionably, without a doubt, but who we haven't seen actually do anything that fashion photographers don't do with 14-year-old models in everyday life.

And it doesn't turn out to be anything nearly so simple as "who is the greater evil" role-reversal. Screenwriter Brian Nelson-a playwright and TV-series veteran whose biggest previous job was the 1997 miniseries 20,000 Leagues Under the Sea-and first-time feature director David Slade-who comes from commercials and music-videos-have more interesting things to say about the dark and light mixture of our human natures. Hayley's plot at a couple of points requires us to accept a few too many unpredictable things falling into place, but those doesn't detract from the arc of the story-or from the painful paths of two indelible characters brilliantly played.

-Frank Lovece