Near the end, however, King drops in a strange paragraph. "We get dozens of angry letters each week, demanding the next book," he writes. "One of these contained a Polaroid of a teddy-bear in chains, with a message cut out of newspaper headlines and magazine covers: Release The Next Dark Tower Book At Once Or The Bear Dies ... I put it up in my office to remind myself both of my responsibility and of how wonderful it is to have people who actually care..."
Like many successful Americans, King can find self-affirmation in the unlikeliest places. But after publishing 40 lurid-jacketed volumes of horror fiction since 1974 - enough of them million-selling to make him one of the world's favourite authors in any genre - King's sang-froid has another, more particular source. He is rather familiar with the attentions of his "constant readers".
Five years ago one of them came to visit. Erik Keene had been reading King's tales of possessed teens and malign graveyards between shifts at a fast-food restaurant in San Antonio, Texas. In April 1991 he drove 2,000 miles north to King's tall wooden house in Bangor, Maine. Keene wanted King to co-author a book with him. King was out, at a baseball game with one of his sons. His wife Tabitha heard breaking glass, and found Keene in the attic, clutching what he said was a bomb. Police had to lay siege to the area. "Usually those people write, they don't turn up," King later said.
Such an incident could be put down to the perils of American celebrity. King is certainly famous enough: having dinner in a restaurant with Bruce Springsteen on one occasion, the anonymously slab-faced author was approached by a teenager who entirely failed to recognise the rock star opposite.
But King's books encourage obsession. They can be more than 1,000 pages long. At least two come out every year (a rate of publication matched only by books about King). And they are often about obsession: a victimised girl's revenge on her high school in Carrie, a pale, car-mad boy and his haunted '58 Plymouth in Christine. In King's stories, grudges are always pursued, threats never abate, and enemies never give up - until the burnings and stabbings of his characteristically drawn-out finales. One, Misery, concerns a writer held hostage in his home by a reader.
And all this occurs in just the kind of north-eastern small towns King and his readers inhabit. He uses local landmarks - a spooky church near his house; a favourite childhood pond, where a body was once discovered - as backdrops for his stories. This intertwining of nightmare and local reality and autobiography has its consequences: millions of readers buy the books; a few seem to think they are true.
KING himself is not that different. All his life he has slipped easily into fantasy. His childhood in Maine was hard: his family never ate desserts. In 1949, when King was two, his sailor father went out for some cigarettes and never came back. But his mother rallied, taking menial jobs and bringing home armfuls of what she called "cheap, sweet vacations" - secondhand paperbacks. She and her son devoured murder stories in particular.
By the age of seven, he was sneaking into drive-ins to watch horror films, too. At 11, already an awkward six-footer, he started a tiny local newspaper with his foster-brother, recommending films and trying out science fiction ideas. Within three years, he was submitting to professional magazines, his imagination boiling with Lord of the Flies and the macabre New England tales of H P Lovecraft.
But publication came grudgingly. He was at the University of Maine studying literature before he finally made the autumn 1967 issue of Startling Mystery Stories. Writing furiously, he took courses in creative writing and rural sociology (for research) and waited to acquire a reputation.
Again, it didn't happen. Married now to Tabitha, his college sweetheart, King graduated from university to a hillside caravan in a cold town called Hermon, "if not the asshole of the universe, then at least within farting distance of it", as he saw it. Struggling with two young children and a succession of low-paid labouring and teaching jobs, he nevertheless flung out five novels - and had five rejections flung back. The short stories he did publish couldn't pay the phone bill. King began "drinking too much".
In 1973 he started a book about a put-upon high school girl who could make objects move or burst into flames by mental effort alone. He threw it in the bin, but Tabitha picked Carrie out again; she was right: he sold the manuscript, first for $2,500 as a hardback, then, as publishers lunged, for $400,000 as a paperback, a figure so bewildering to King that all he could think to buy his wife as a thank-you was a $29 hair-drier.
He had his moment. After decades as a pulpy thrill for ill-adjusted teenagers, horror became mainstream with the success of films like The Exorcist and The Omen. But Carrie was skilful, too, slipping its premise on to page one, painting its protagonist more subtly than the genre usually allowed, and swelling to its apocalyptic finale, as she set her high school on fire on prom night, in a swift 200 pages.
King then made a success into a career by sheer output. Churning out 2,000 words a day - a quantity he maintains - he followed Carrie with Salem's Lot, an updated Maine vampire tale, and The Shining, a traditional haunted-house story moved to the top of the Rockies. All three became films; after thousands of nights at the drive-in and watching late-night television King instinctively saw the potential synergy between book and screen. "Stephen speaks to readers who aren't spoken to by much else," says his editor, Chuck Verrill.
The production line for what King calls his "literary equivalent of a Big Mac and large fries" has run at peak capacity ever since. King writes enough words for seven normal-length novels a year. "Talent is cheaper than table salt," he said once. "What separates the talented individual from the successful one is a lot of hard work."
King makes sure his writing never gets too shocking, favouring eternal fears and happy endings in his reassuringly old-fashioned small towns rather than modern urban horrors. And his handful of fright-free vignettes have also become films, with Stand By Me and The Shawshank Redemption carrying his name far beyond horror circles. Unusually for his genre, half his readers are women.
All this diversification has had its disadvantages. A lack of quality control has seen some of his books - which tend to be more haunted than gory - crudely hacked up into bloody straight-to-video fare. The middle- aged spread of his writing into longer, more fantastical novels and Roald Dahl-style short stories has lost him some of his horror-writer's reputation. "The real fans think he's a bit passe," says Allan Bryce, editor of the horror magazine Darkside. "He's a mainstream writer who dabbles."
Yet King has created a fearsome appetite among the faithful. Between 1977 and 1984 he published five rather more conventional novels under the pseudonym Richard Bachman, complete with invented biography. So keen- eyed and hungry were some of King's fans that they soon grew suspicious; onesearched publishers' forms in the Library of Congress to reveal Bachman's identity.
He removed his phone number from public listing as early as 1976, and now writes in a rented bungalow several miles from his home. After the Keene break-in, he had the fence round his house extended, his gates padlocked, and a code-controlled entrance installed.
Yet behind his gates King retains an affable, relatively ordinary life. Although he writes nearly every day, except his birthday, Easter and Christmas (he is a Methodist), he fulfils his quota so quickly - before lunch - that he has plenty of time to play tennis with his children. He spends little of his income, said to be more than pounds 15m a year, preferring "to know my ass is going to be covered" - mindful of his draughty years in that hillside caravan.
Like the Midwestern adolescents he writes for and still resembles, he wears jeans and T-shirts and listens to old-fashioned hard rock as he works. When his local music station announced it was switching to something softer, he bought it and re-instituted the Rolling Stones. "He's a big jovial enthusiastic person," says Greil Marcus, a music critic who sings with King in a rusty writers' band. "He looks like a horror character, though."
And King does play the part. He once did an American Express advertisement, emerging gaunt from the shadows with a raven on his arm. He likes to haul his hulking axe-murderer's frame on to his Harley-Davidson and appear, unannounced, at remote bookshops. His house, moreover, does not hide its occupant's identity too hard: cast-iron vampire bats guard the drive. No one should take them too seriously.