From the cousin who slept with a crucifix under the pillow for months to the couple who nearly split after a trip to the cinema in 1973 to the friend who swore that even the original Warner Home Video cassette box looked evil, almost everyone has a story about seeing - or not seeing - 'The Exorcist'. It is, as its author William Peter Blatty said in the 1998 documentary 'The Fear of God', a film which delivers "that very precious commodity: a powerful emotional response".

While Daniel Stamm's 'The Last Exorcism' isn't as classy as Blatty and director William Friedkin's work, lots of stories will spring up around it too.

Shot documentary style, the film follows the work of Cotton Marcus (Fabian), a teeth-and-trousers Louisiana preacher whose charm is equalled only by his doubts about what he's doing. On the pulpit since childhood in his father's church, Marcus has hit a wall with his faith and is more egotistical showman than humble spiritualist. He tells the makers of the movie that while he's performed many exorcisms he thinks those he's 'saved' are suffering from psychological problems not possession - but hey, they're a good payday and if everyone goes to sleep happy what harm.

Marcus receives lots of letters requesting his help with demons and, picking one from the pile, agrees to take the film crew with him so they can see the tricks of the trade. The trio travel to the sticks where widowed farmer Louis Sweetzer (Herthum) is convinced that daughter Nell (Bell) is possessed - animals have died, strange voices have been heard and Nell's paintings are a little, well, odd. Son Caleb (Landry Jones) isn't exactly a ball of fun, either.

Marcus isn't sure if the girl, her father or brother needs his help the most but, needing the money, decides to put on his show for the family and crew. Exorcism successfully completed, he sticks his few hundred dollars in his back pocket and heads for the motel.

Then things start to go very wrong, very quickly.

The only thing harder to do than good comedy is good horror, but even the most hardcore of scary movie fans may take a little jump in the seat as the pastor's story plays out. Like last year's 'Paranormal Activity', 'The Last Exorcism' shows that a simple idea done well can overcome a small budget, a cast of unknowns and a too-cool-for-school audience. The sense of doom is colossal and with every scene the desire to shout: "Get the hell out of there!" grows stronger. There's more chance of you bolting for the exit than Cotton Marcus.

'The Last Exorcism' is one of 2010's more memorable movies, but a few flaws prevent it from being a classic. The use of music, which sounds like someone tuning up a cello, is unnecessary and pulls you back into the real world and out of the 'documentary trance'. A bigger problem is that there was more suspense and tension to be wrung out of certain scenes than Stamm manages and, having come up with an ending which is suitably full-on and actually shocking, he rushes it.

That said, as the nights close in, it's nice to have a film like this waiting in cinemas - grim, menacing and there for you to find out if you have the guts to watch it.

Sometimes it's handy to have a spare pair of pants in your bag.

Harry Guerin