THE TOMMYKNOCKERS By Stephen King Putnam. 558 pp. $19.95

EARLY ON in this new novel from the king of contemporary horror fiction, a writer of pulp westerns modifies her battered Underwood manual typewriter (under the guidance of an alien presence from space) with four D-cell batteries and a radio circuit board so that she can simply think the words onto the paper. Relieved of the tedium of typing, she writes a 400-page novel in three days, much of it while she sleeps. Given the number of his novels and the regularity with which he publishes them, one wonders whether Stephen King might not also have a "thought writer" at his disposal.

Readers of The Tommyknockers only get to read the first four paragraphs of The Buffalo Soldiers, the novel by Roberta "Bobbi" Anderson, the hapless writer who discovers an alien spaceship in the woods near her Maine farmhouse. But four paragraphs is enough, for The Buffalo Soldiers just isn't very good. In that regard, it's got a lot in common with The Tommyknockers, which isn't very good either. It might have been; somewhere inside this bloated, self-indulgent hulk of a novel is a taut thriller, tribute perhaps to low-budget science fiction movies of the 1950s and '60s like Invasion of the Body Snatchers. The pity is that King never lets that taut thriller get out.

The Tommyknockers starts out promisingly enough with Bobbi Anderson literally stumbling over an exposed edge of the buried spaceship. Something about the ship draws her to it, and Bobbi becomes obsessed with digging it up. As more of the ship's hull is exposed, and it oxidizes, the airborne molecules begin to have a peculiar effect on Bobbi and the people of Haven, the nearest small town.

Meanwhile, Bobbi's friend and former lover, an alcoholic poet and sometime anti-nuclear activist is in the midst of a binge that gets him thrown off the New England Poetry Caravan tour. A few mornings after, Gardener wakes up feeling that Bobbi's in trouble and needs him. Heeding his intuition, Gardener makes his way to Haven, where he discovers Bobbi, exhausted from laboring night and day to dig up the ship, creating her souped-up Underwood typewriter and making it so that everything in her house -- hot water heater, lights, appliances -- can run on D-cell batteries.

The people of nearby Haven, changing as Bobbi is changing, all seem to be inventing things too -- the village postmistress devises a machine that sorts letters, even misaddressed ones; the postman's wife rewires the television to electrocute her husband (who's been having an affair with the postmistress); and a 10-year-old boy intent on learning how to perform magic tricks makes his little brother disappear. Permanently.

Under the influence of the ship and whatever it carries, Bobbi and the people of Haven are all becoming Tommyknockers, as Gard decides to call them. He himself is not completely immune to the ship, though a metal plate implanted in his head after a skiing accident spares him most of the effects. And though Gard is horrified at what is happening to Bobbi -- she's losing her teeth and undergoing other physical changes best not discussed in a family newspaper -- he agrees to help her dig up the ship.

JUST WHY Gard decides to stick around and help isn't quite clear -- it has something to do with his love for Bobbi and with his half-formed conviction that there might be something in the ship that could be used for the good of humanity -- and that points to some of the problems with The Tommyknockers.

Gard's motivations, and those of many of the other characters, are unclear. Moreover, the novel seems without a center. Bobbi is on stage for the first 50 pages, then Gard for twice that, then the people of Haven in a series of momentum-derailing portraits. It's as if King couldn't decide whose story it was, and the result is a series of disjointed vignettes involving cardboard characters. These episodes are occasionally entertaining, but more often filled with flatulence, feces and menses (as well as more traditional blood and gore) and pointlessly horrific.

Perhaps more than other kinds of fiction, fantasy, horror and science fiction demand the reader's willing suspension of belief. Not only are the things that happen improbable, they are, after all, things we would not admit wanting to happen. The onus is on the writer, then, not merely to create an irresistible inevitability in his plot, but to furnish a plausible world and plausible characters with whom the reader can identify, no matter how implausible the things that happen to them there.

For the most part, King's work -- whatever its lack of subtlety -- has always been possessed of energy and power. In his last book, Misery (a trim middleweight compared to this obese opus), a writer is kidnaped by one of his fans and forced to revive the killed-off heroine of the romance series that made him famous. In it, the writer assesses himself, but King could just as easily have been writing about King: "There's a million things in this world I can't do. Couldn't hit a curve ball, even back in high school. Can't fix a leaky faucet . . . But if you want me to take you away, to scare you or involve you or make you cry or grin, yeah, I can. I can bring it to you and keep bringing it to you until you holler uncle. I am able. I CAN."

The Tommyknockers is no proof of it. King pulls out all the stops -- besides the alcoholic everyman doing his best in an extreme situation, there are the kindly grandfather, the lost little boy, and the tough, but honest, cop. None ever really comes alive on the page. And despite his use of the honorable tricks of the trade -- weaving together three or more stories and interrupting a section of the narrative just before the climactic moment -- the book lacks intensity. Instead of being swept up in the flow of events and carried by the rush of the narrative, the reader plods on, occasionally excited, more often disappointed, continuing in the hope that The Tommyknockers will hit its stride and turn out to be the kind of story he's learned to expect from King after all.

It never does. Worse, it presents evidence that King has begun to take himself seriously in the worst way. It's not just that the novel could have used a firm editor to trim a third of its bulk, but King's attempted to create a kind of bargain basement Yoknapatawah County. There are references to other of his novels -- The Dead Zone and to the movie version of The Shining ; the clown who was It in It makes an appearance, as does a character from The Dead Zone. And King refers to himself as "that fellow who lived up in Bangor" who wrote novels "all full of make-believe monsters and a bunch of dirty words."

That fellow's still writing them, but more and more they don't seem quite as good as they used to.

David Nicholson is an assistant editor of Book World.