There are three types of people who frighten me: people who have an intense love of popular romantic fiction; people who can't bring themselves to swear under any circumstances whatsoever and instead invent their own homespun swear-lite; and people whose heinous actions are supposedly ordained by god. All of these afflictions hint at an arrested development, an inability to deal with reality and a barely suppressed rage. So, needless to say, in light of her suffering from all three of these disorders, Annie Wilkes is a woman to be extremely fearful of.

But of course, at first, she seems so nice. She rescues Paul Sheldon from freezing to death after he crashes his car in a blizzard and then she gives him medical treatment in her own home. But no sooner has she opened her mouth than she's declaring him 'The World's Greatest Writer' and calling him a 'literary genius' - this she says of a man who loathes his own work and a man who hates the way he's become a manufacturer of bland product rather than a writer expressing himself. But even more worryingly she apologises for making him feel "oogy". The warning bells ring loud and clear.

But Annie's insanity doesn't get its first overt display until after she's begun reading the manuscript that was pulled from Paul's car – it's more personal work and it's a breakaway from the Misery tripe he's been getting rich off. She admits that it's well written but she says the profanity bothers her. And she flies off the handle completely when Paul insists that slum children do indeed swear. It's a great scene and Kathy Bates' delivery is perfect. It's both comical and unnerving.

However, more frightening than the loss of temper is the way that Annie apologises. She tells Paul she loves him. Paul's sphincter must be playing all kinds of tricks.

After this, the film plays the humour of the situation for a little while. We get a funny scene where Annie introduces Paul to her pig (which, surprise, surprise, is called Misery) and then there's a fantastic bit where Annie is talking about her failed marriage. At first it appears to be a serious scene, but then halfway through her spiel we find out that Paul has been urinating into a bottle while listening to her prattle on. And it becomes even funnier when Annie begins lecturing Paul while swishing the bottle of urine absently in her hand. The weird humour helps make Annie seem more believable (and therefore more terrifying).

Another funny moment is when Annie is talking about 'Misery's Child' (unbeknownst to Annie, it's Misery's final book – Paul's killed her off). She's about halfway through and she calls it divine. And then she asks this wonderful question: "What's the ceiling that dago painted?" "The Sistine Chapel," is Paul's incredulous response. "Yeah, that and ‘Misery's Child’, those are the only two divine things ever in this world." It's a funny moment because it reveals so much about Annie's character – she's totally ignorant and she's casually racist, too (so much for being clean and pure).

But the humour in the film comes to a bit of a halt when Annie finishes 'Misery's Child' and finds out about Misery's death. She terrorises Paul as he sleeps and then in the morning she makes him burn the manuscript of the new non-Misery book he's written. In a typical fundamentalist Christian sort of way she insists he must rid the world of this 'filth'. And in one of the most casually frightening bits in the film she walks around the bed absently squirting lighter fluid on his legs. It's only after this that Paul is persuaded to burn his book. And the look on Caan's face is wonderful. He's both completely heartbroken (he might as well have burnt one of his own children) and filled with rage – after this he quietly declares war on Annie.

But after the burning, the humour returns. However, it becomes more closely linked with the horror. For instance, there's a darkly amusing moment when Annie loses her temper when Paul shows that the expensive paper she's bought for him smudges. She begins shouting and then slams the paper into his lap. And then there's the rant she makes about chapter plays ("He didn't get out of the cockadoode car!"). I mean, it's nutty enough that a woman has her favourite writer held hostage in her house and she's making him write a new Misery book for her, but it's blackly comic that she becomes a violent one-person focus group. It must be every writer's worst nightmare – you've got to tailor your work to the whims of a nutball.

A fabulous scene illustrating how precarious Paul's situation is is when Annie begins talking to him in a depressed state. She goes on about how the rain gives her the blues and she says how fearful she is of losing him. And then she pulls a gun out. Again both Caan and Bates are tremendous. Caan barely suppresses his alarm and Bates casually says that she might put bullets in the weapon. Once again it's a small off-hand moment that is horrific in the implied threat.

And the famous hobbling scene is made more unsettling by the way Annie tells Paul she loves him after she's broken his ankles. Nothing says "I love you" like smashed feet, eh?

But although Bates rightly gets a lot of attention, I really must give Caan a lot of credit for his performance. He conveys the helplessness of his situation superbly and it's such a cathartic moment when he finally stuffs the charred remains of 'Misery's Return' down Annie's throat. But if I'm nitpicking I do have to say it's a shame that the fight at the end has the clichéd 'back from the dead' moment. It's the only wrong step in an otherwise fantastic film.