A powerful psychological thriller which keeps on confounding expectations, the film borrows heavily from a famous fairy tale, which it cunningly turns on its head.

In this disturbing, edge-of-seat story, a clever, cold-blooded, singleminded Little Red Riding Hood manipulates, imprisons, tortures and ultimately exacts a terrible revenge on a Big Bad Wolf.

Set in contemporary Los Angeles, Hard Candy begins with a now-familiar domestic sight — a teenager’s fingers tap out message after message and fires them into an Internet chat-room.

The hands on the keypad belong to 14-year-old Hayley (Ellen Page), who, after forming an online relationship with 32-year-old fashion photographer Jeff (Patrick Wilson), agrees to meet him for a coffee at Nighthawks, a diner where another girl, now missing, was last seen.

Hayley is flirtatious, but is bright, sophisticated and seems to be able to look after herself. And anyway, Jeff is friendly and unthreatening.

But all the time, we, the audience, knowing what we know of real-life paedophiles grooming children via the Web and what can come of such rendezvous, have alarm bells ringing in our heads.

However, Hayley ends up at Jeff’s sleek modern house in the remote Hollywood hills.

He fixes her a cocktail, but Hayley’s a smart cookie. She refuses on the grounds her parents have warned her to never drink a drink she hasn’t mixed herself.

Jeff laughs smoothly, and allows Hayley to mix drinks for both of them. And this is where your worst expectations are turned upside down, although the tension doesn’t let-up one iota. The girl slips the man a Mickey.

Jeff wakes up strapped to a chair and, as he surfaces from his stupor, Hayley explains to him the scenario.

She knows he is a paedophile and that he has been following her from Internet chat-room to chat-room and grooming her for that first face-to-face encounter, the visit to his home, and then God knows what.

But, in reality, Hayley has been stalking Jeff. She wants him to confess the nature and full extent of his perversion; she wants him to reveal just what he had to do with the disappearance of the Nighthawks girl; and she wants to make certain he never carries out such offences again.

Hard Candy, a debut feature by British director David Slade, is an unsettling movie from the start. In the first scenes, close-up camera work fills the screen with Hayley or Jeff’s face, contrasting the pleasantries and trivia of their early dialogue, with a visual sense of physical weight, dominance and danger. This is heightened when the camera occasionally pulls back to highlight slight Hayley being towered over by Jeff.

Of course, when the girl turns the tables on the man, the tension takes off in another direction. Just what does Hayley plan for Jeff? And is she right in her assessment of him?

For most of the film, Jeff’s sexuality and the nature of his crimes, if any, are in doubt. There is even the nagging thought he could be innocent.

After all, Hayley on her own admission, is crazed.

There are also a number of questions over Hayley’s motivation, which are only resolved in the movie’s final seconds. Did she know the missing Nighthawks girl? She tells Jeff, no. Yet she has fixed on her victim for some very definite reasons.

This award-winning independent movie is a high-impact cracker, in almost the same must-see bracket as United 93. It has a clever plot and it’s expertly directed (in fact, remarkably so for such a big-screen novice as Slade), but the acting at the heart of this two-hander is what it is truly awe-inspiring.

VERDICT: A grim reworking of Grimm.