Posterity has a fine-tooth comb, and it often takes the creation of an archetypal character - a Tarzan, Frankenstein, Dr Jekyll or Sherlock Holmes - to give it something to snag on to. Figures such as these dwell in our imaginations long after the heroes of ostensibly subtler works have slid away, and it is in their nature to loom larger than the authors who conceived them. So no one should be surprised that Hannibal Lecter is a more memorable figure than Thomas Harris. In two books (Red Dragon and The Silence of the Lambs) Lecter both summarised and symbolised the modern phenomenon of the serial murderer.
Horror, it seemed, was coming home, and it wasn't goblins or hellhounds we had to fear: it was ourselves. The forensic and procedural world seemed real - part of a well-reported trend in killing for kicks or company - but Lecter was mythical. With his maroon eyes, sharp teeth and prison-pale complexion, he was presented as a child of Dracula. Where the count was encyclopaedically learned, having stalked his sorcerer's battlements for centuries, Lecter was supernaturally perceptive. To inhale the air he breathed was to be mesmerised, invaded and fatally poisoned.
The genius of Harris's conception was that Lecter remained dangerous even when incarcerated. The briefest conversation with him was a perilous pas de deux with something monstrously clever and malign. He repudiated the profoundest tenets of civilisation while emphasising its surface courtesies. He was a dandy, an aesthete and a tease, and he was unsurpriseable; he knew everything. The threat he posed was intellectual; even bound and gagged he seemed capable of anything. He could divine a woman's perfume through thick glass or persuade a cellmate to swallow his own tongue, simply by whispering to him.
In Jonathan Demme's film, Anthony Hopkins emphasised the decorous and playful comedian in Lecter, but in the books the viciousness thumps closer to home. Apart from his own grotesque savageries, Lecter "collects church collapses, recreationally" - he's a performance nihilist, delighting in the divine cruelty of fate. There have always been literary theories to the effect that murder stories are unjustly relegated in the literary pantheon, and Harris gave them a vivid new kick. His books were unputdownable, but aside from that they were trim existential dramas about the nature of civilisation. "There is no murder," says the author at the end of Red Dragon. "We make murder, and it matters only to us."
He's a grand writer, in other words, and grand things have been expected of the third instalment. It has been a long time coming: 11 years. Like Lecter himself, it seemed to have gone into hiding, adding to its allure. When it began to appear on the book trade's radar half-a-dozen years ago, the blips looked thrilling. No one knew for sure (Harris guards his privacy), but apparently the new book was going to pitch Clarice Starling and the FBI into a macabre duel with Lecter. She would be pursuing new serial killers and would begin to see Lecter's footprints at her crime scenes: he'd beaten her to it, killing the killers, helping and mocking her at the same time. She would have to forget the pawn vampires and go after the king.
It sounded perfect. The tussle between huge corporate resources and a single wild intelligence would unleash Harris's brilliant way with investigative suspense and allow him to refine the idea that it takes a murderer to catch one, that both Starling and Will Graham (in Red Dragon) have unusual gifts distinguished from Lecter's savage urges by the thinnest of civilisation's thin lines.
The sad truth is that Hannibal is not that story. Harris has resolved instead to take us further into the cryptic heart and palatial mind of Lecter himself. He wants us - literally, if that is not giving too much away - to sup with the devil. There is plenty of commercial logic to the idea - stand by for some heavy Lecter merchandising when the film comes out - but in literary terms it is very sad. The more we learn about Lecter, the less resonant he becomes. In gaining his freedom, in shopping for expensive soap and driving a vintage Jaguar, he loses the magical potency with which he outwitted the world's best efforts to restrain him. Not since Samson lost his hair has a warrior been so crudely brought down to earth.
As if to compensate, Harris exaggerates both Lecter's refinement - fine wines, rare cheeses and snob labels - and the Grand Guignol aspects of the story. There's an obscene swine farmer hooked up on life support, who plans to capture Lecter and feed him to his wild pigs; there's a Roman policeman destined to re-enact his ancestor's medieval demise, swinging above Florence with his entrails hanging out. There's a mad woman bodybuilder, an unbelievable Sardinian mafioso and a ferocious moray eel with jaws "like boltcutters". And then there's Clarice Starling, carefully ushered towards the altar to become Dracula's bride.
If anything, Harris pushes this analogy even more explicitly than before. The manipulation of Starling introduces the idea that Lecter, like Dracula, can reproduce himself or at least seduce others into his family. There are echoes in the way he glides through Italy - snacking on human prey - of Dracula's own journey from the superstitious Carpathians to dull old England. It may even be possible to see his wanderings as some sort of critique on America's murder culture, homicide being such an important US export in these violent times.
Clearly Harris was not happy for Lecter 'n' Clarice to become a soap, a pair of lovable buddies who never change, no matter how extreme the storms they pass through. But he has paid a heavy price for his ambition. Lecter, we learn, is haunted by the memory of his sister's being torn from his grasp by hungry soldiers who have run out of deer to kill. This is awful but ordinary. The whole point of Lecter was that he was not recognisably human: he was a high-powered mutant, an awful possibility. Now he is just another crazed avenger, a bloodthirsty killer able to turn on the charm when it suits him. The wolf becomes a pit bull.
All of which may make the book sound a mess. Harris remains a formidable writer, though, and there is a lot of demented inventiveness in his icy narration. But despite his having produced two such suggestive models of restraint, his more Gothic impulses bleed over the canvas. When Lecter opens his wine he removes the cork "as carefully as he might trepan a skull". Lecturing (as with a name like his he should) in Florence, he quips: "It might be interesting to take up the matter of chewing in Dante." Travelling incognito, he joins a package tour called "Old World Fantasy". These are clever, but only bon mots - we can see them winking.
It is tough for Harris that he has, in his previous works, set the bar so high. But in trying so hard he merely makes explicit what was once a superb shiver. He clearly feels he ought not to flinch from the barbarous details, and the result is a horror show. He also amplifies his streak of contempt for so-called civilisation: Lecter feels his own "modest predations" pale beside those of God, whose "wanton malice" is "beyond measure". This disgust with the soft illusions of modern life has been there from the beginning. Red Dragon ended with a razor image of nature's barbarity. The hero recalls a ramble he took at Shiloh, the civil-war battlefield where so many were massacred. He watches a car run over a chicken snake, leaving it broken-backed and wriggling in the heat. "The snake looped on itself. He stood over it, picked it up by the end of its smooth dry tail, and with a long fluid motion cracked it like a whip. Its brains zinged into the pond. A bream rose to them."
There's something unspeakable about the abrupt economy of these terse phrases. But in Hannibal the style becomes baroque, rich to the point of cloying. Lecter himself, an expert chef, would have blushed to leave the gas so high. Hannibal is a good 100 pages longer than its predecessors and has a thinner plot. Who would have thought that the taste for human flesh would prove so fattening?
Robert Winder, a columnist on the "Independent on Sunday", is the new lead reviewer of the "New Statesman". He will write monthly