Here is a thoroughly absorbing supernatural fairytale about good and evil living under the same roof. Decent men work with cruel ones in this movie, and a creature with miraculous healing power winds up in a place inextricably linked with death. Perhaps that's the most appropriate place to witness him.

The location is E-block in a 1935 Louisiana prison, where inmates await the electric chair, and the condemned man's 'last mile' has been nicknamed 'the green mile' after the lime-coloured linoleum on the floor. We meet some of the guards: Paul Edgecomb (Tom Hanks), Brutus Howell (David Morse), Dean Stanton (Barry Pepper), Harry Terwilliger (Jeffrey Demunn), Percy Wetmore (Doug Hutchison).

All of these, except for the slimy Percy, who got his job because of a powerful relative, are good and patient men, who are firm yet kind to their prisoners. They view their role, correctly, as being a calming influence on inmates who would be dangerous if they got too nervy. "Think of this place as like an intensive care ward in a hospital," advises Paul.

One of the new guests is John Coffey (Michael Clarke Duncan), a gigantic black man who has been convicted of the rape-murders of two young girls, but seems to exude simplicity and goodness, and turns out to have a very special ability. Other odd plot points creep up and get a fair bit of attention, such as a urinary infection Paul suffers from, an unusually talented mouse, and a boorish prisoner named Wharton. We wonder what significance all these things could possibly have, and then finally they come together in a climax of moving drama, religious symbolism and clever epilogue.

My vague descriptions are intentional. "The Green Mile" does not announce what it is about, but drops little clues here and there, letting its story unfold carefully, intriguing and enveloping us with its atmosphere. That is why virtue and depravity are set at equal levels throughout the film; the conflict is needed to create quietly gripping tension. And it is exactly how the original Stephen King source material worked -- slyly revealing the story by taking things slowly, letting us settle in, earning our care.

King released "The Green Mile" as a novel in six parts, leaving intervals of several months between instalments, engaging his public in a guessing game about what direction the material would go in. Even if you read the whole series at once, as I did, you still felt led through it slowly, because the author's prose was so delicate and detailed. The film captures this remarkably well; Frank Darabont, the writer and director, who previously adapted a King work into the great "Shawshank Redemption", recognises deliberate pacing as an essential part of this story, and never falls into the trap of condensing it into a series of meaningless spooky events.

If only Darabont had bought the rights to Alex Garland's "The Beach", instead of that hyperactive boor Danny Boyle! The way he lets "The Green Mile" develop involves us with the intimacy of a good book. The film is three hours long, but contrary to the opinions of some critics, extensive length is not the film's problem, but its appeal. We get so immersed in the routine of life on the 'green mile' that when paranormal activity starts to happen, we accept it, and are amazed along with the characters. Audience members prepared to sit still and give the movie a chance will be handsomely rewarded.

Not that you'd think it from the ads. This week two brilliant new releases, "The Green Mile" and "Three Kings", have been so badly misrepresented by their television commercials that many cinema-goers will be persuaded to stay at home. Darabont's film has been portrayed as some sort of mawkish sentimental drama, with its scenes of good fable taken out of context, and made to look like bad attempts at realism. This is a movie that knows exactly what it's doing, and while it does have its fair share of tender moments, they're needed to balance out the brutality. One scene, for example, graphically depicts an execution Percy has rigged to go wrong, and is one of the most horrifying single moments ever shown on film -- my hand instinctively jumped to cover my eyes. I was able to remove it, and look on, but it really means something when a film can trigger involuntary defensive movements.