Ideal Holmes exhibition

Arthur and George, by Julian Barnes, is already being talked about as a Booker winner, and it's easy to see why. This is the kind of book Arthur Conan Doyle could never have written (far deeper psychological insight, far more sophisticated use of irony and awareness of the limits of fiction), yet it has all of the master's narrative panache.

So here we have Arthur Conan Doyle, growing up in shabby-genteel Edinburgh, conscious that although circumstances compelled his mother to take in lodgers, she was descended from Ireland's nobility. Go far enough back on his father's side and, instead of being a drunkard, he is a descendant of the Dukes of Brittany.

Chivalry matters. Injustice has to be fought against. Conan Doyle is a man of great certainty living in a similarly self-confident age, and when he starts writing, his great detective hero reflects this. All cases can be solved by concentrated thought; all injustices righted by moral courage. In time, as science strides into the territory religion used to occupy, even that which lies beyond death itself will, he is convinced, soon become clearer with the appliance of science.

In contrast to the empire's second-most influential writer (after Kipling), George Edalji is altogether less self-confident. The colour of his skin has a lot to do with it: apart from his father, an Anglican minister in the village of Great Wyrley, there are few other Parsees in Staffordshire. Friendless where Doyle is clubbable, prim and restrained where Doyle is extrovert and sporting, Edalji is a loner who takes solace in the certainties of law. He qualifies as a solicitor, commutes by train to Birmingham. There are the odd glances and whispered comments but he can surely rise above them.

Except he can't. Because in Great Wyrley, as the 20th century begins, a maniac starts mutilating cattle and animals. He leaves notes taunting the police. Children and girls, he warns, will be next.

Already the police have a prime suspect. He's the person they also blame for the string of hoax letters that have already brought coffins, pear trees, gallons of black paint, wedding dresses, horse manure, crates of Champagne and whole shopfuls of other unasked-for goods to the front door at Great Wyrley vicarage.

The person the police have fingered from the start is Edalji. This is distinctly odd. How can anyone possibly believe a law-abiding solicitor could put his family through such a nightmare? How could they even think that he would then roam the fields at night disembowelling horses and cows? After all, as his father the minister pointed out, each night his son slept with him in the same locked bedroom. But doesn't that raise even more questions than it answers?

Look back first, though, at Arthur and George. Already, for all their contrasts, they have some things in common - a zeal for justice.

When Edalji is arrested, tried, found guilty and imprisoned, when he writes to the great campaigning writer, the plot is already turning smoothly like an oiled lock. But for Barnes - a thriller writer himself in the 1970s and 1980s under the nom de plume Dan Kavanagh - this is just the framework for a novel. There's far more to it than that.

Characterisation first. Offhand, I can't think of a novel I've read in the last couple of years where the characters walk off the page as unstoppably as they do in Barnes's portrait of Doyle and Edalji.

You can see Edalji trying to cling on to his faith in justice, pathetically trying to insist on the correct pronunciation of his surname ("It's Ay-dlji, not Ee-dal-ji") yet watching as his evidence twists and turns in the lawyers' courtroom speeches, imperceptibly peeling away from what he remembered and turning into something else altogether. You can imagine Doyle, whose first wife is dying, similarly tormented by his unconsummated (anything else would be unchivalrous) love for another woman. Skilfully, Barnes weaves even more complicated ideas into Conan Doyle's mind.

Linked to two deaths - his father's and his first wife's - his investigations have also turned metaphysical. The great detective's creator has now turned to spiritualism and has Death in his sights. Can be bring the Grim Reaper to justice too?

And if we've already mentioned Barnes the detective writer, we should now mention Barnes the researcher, the kind of luminously intelligent writer who could produce a book like Flaubert's Parrot (in which he described making sense of a person's life as like making a fishing net - essentially tying together a bunch of holes). With such a writer, the reader expecting historical as well as emotional accuracy is in safe hands. You want political, social, legal context? You want Holmesian detail? You want to understand how spiritualism started up in an increasingly rational age? You want all that woven into the plot as subtly as the late Victorian language also is? (Did I mention that Barnes's first job was as a lexicographer?) It's all here.

The man himself will, I know, forgive me for introducing him so late into this piece. He'll understand why. We meet, as we've met once before, in his local pub, the Lord Palmerston, which is where all of his London interviews take place and where all of his interviewers seem to leave with the adjectives "effortlessly intelligent", "utterly charming" and "mildly laconic" swimming around between their synapses. They're all, as far as I can gather, absolutely correct, although I'd like to add "politely unknowable" to the list.

When I play back our hour-long conversation, it goes like this.

Me: "I've got this new digital recorder this time. Not terribly sure how to work it."

JB: "I think it's recording already."

Me: "No, I think you have to press." (Hits button.)

Digital recorder: "Pffft."

Luckily, I took notes too. So I know how Barnes first came across the Edalji case. Reading the historian Douglas Johnson on the Dreyfus case, he was intrigued by a reference to a case of a miscarriage of justice that had divided the English just as the treason charge against the Jewish officer had divided the French. Everyone who studies the Third Republic knows about Dreyfus, yet the Edalji case seemed to have disappeared from histories of Edwardian England.

"I started reading up on it, and it didn't read at all like a dead case: the issues seemed to be completely relevant today - and, after all, it led to the creation of the Court of Appeal. But as George points out in the novel, that's the difference between the English and the French: while France is a country of extremes, Britain sorts out problem pragmatically."

He started writing the book with the marvellous set-piece at the end, when Edalji attends a Spiritualist memorial service in the Albert Hall after Conan Doyle's death. "At the time I didn't know whether George was actually around in 1927, and so I was quite prepared to keep quiet about it if he wasn't - although he actually lived right up to 1953. But early on I felt the rhythm of the story, its weight, its tone.

"The hardest parts to write were when I had to make the historical record about such facts as Doyle's schooling part of my own fiction. It was a lot easier with George, when there were so few facts to go on. It's much easier to imagine his whole inner life when all you've got is his book on railway law."

Conan Doyle's spiritualism is one area in which Barnes's novel goes against the received interpretation of Doyle conversion to the movement. "What's usually said is that it only happened in the wake of his son's death in the First World War. But look at the evidence. In 1897, the year his father dies and the year in which he tries to kill off Holmes, his list of books and brochures to read includes 74 just about spiritualism."

When I look at my notes, I did indeed scribble down a lot of facts Barnes gave me about Arthur and George. But the real reason this is such an enjoyable book isn't there. It's like a scene in which Erdjali looks down at the 6,000 spiritualists in the memorial service for Conan Doyle, all of them straining to see the sign he promised he would send them of the existence of an afterlife. The harsh (for them) fact is that there is no sign. Or if there is, it is invisible to them, just like the links of friendship and respect that have drawn them together in that service in the first place.

In Arthur and George, that equally invisible but effective link, the thing that draws the reader in, is that Barnes is showing us just what fiction can do and up to what point we can believe in it. We know about Sherlock Holmes, so we feel we know something of the mind of his creator. Yet when Conan Doyle acts like Sherlock Holmes himself, with all the audacity of fiction, he almost ends up doing more harm than good to Edalji's cause. Real life has a messiness that fiction can never catch, no matter how hard it tries.

But in unravelling the complexity of a very real case in fiction; in pulling our sympathies first one way and then the other, so that we are led to doubt Edalji's innocence one minute just as clearly as we are made to be convinced of it the next; in subtly shading in the differences between the verbs "believe", "think" and "know"; in doing all of that with superb characterisation, riveting dialogue and all the while giving us a totally credible context, Julian Barnes makes an outstanding case for what the novel can do.

Arthur and George, by Julian Barnes, is published by Jonathan Cape at 17.99. Julian Barnes is at the EIBF on Saturday 13 August.