By Douglas Adams

Simon and Schuster. 247 pp. $14.95

Douglas Adams, Britain's merry prankster of pseudo-science fiction, has served up laughs and book sales galore with his "Hitchhiker's Guide to the Galaxy" series. Now, after four novels of intergalactic high jinks, he has at last moved on to an apparently different kind of book. If only because Adams is such a likably good-natured writer, "Dirk Gently's Holistic Detective Agency" is the sort of novel that the reader anxiously wishes to succeed, even though he soon knows that it will not.

Adams' story concerns a nerdy computer programmer named Richard MacDuff who, summoned back to college by his former tutor, stumbles one dark and not-so-stormy night into a Chinese box of mysteries: foreboding quotations of Coleridge, an inexplicable magic trick, a horse locked in a third-floor dormitory bathroom, a bizarre murder and a rather pesky ghost. Lurking ominously in the background is the Electric Monk, a futuristic labor-saving device that has taken on a life of its own: "Electric Monks believed things for you, thus saving you what was becoming an increasingly onerous task, that of believing all the things the world expected you to believe."

Enter MacDuff's former school chum Svlad Cjelli, a k a Dirk Gently -- scion of Transylvanian high society, affable con man and putative investigator extraordinaire. His gainful employment consists principally of pretending to pursue lost cats at the expense of elderly widows. No Sherlock Holmes -- not even Inspector Clouseau -- Dirk Gently declines magnifying glass, fingerprint powder, all the traditional tools of detection. Instead, he has a world view: "What we are concerned with here is the fundamental interconnectedness of all things ... I see the solution to each problem as being detectable in the pattern and web of the whole."

Adams' playfully self-conscious prose and urge for flippant cosmic satire owe much to Kurt Vonnegut -- and, given their exercise at length in the "Hitchhiker" books, they begin to wear thin here. Indeed, although the exploits of MacDuff and Dirk Gently appear to invoke the "occult detective" novel popularized at the turn of the century by Guy Boothby, William Hope Hodgson and Sax Rohmer, they soon read like a throwback to a more recent vintage -- the "Hitchhiker's Guide" itself. Before we know it, spaceships are circling the Earth in search of our amusement, and characters are spewing forth about quantum mechanics and the space-time continuum while saving the human race from extinction.

Adams is a transactional humorist, at his best when characters go one-on-one, ranting at (and more often than not, past) each other on subjects from the arcane to the mundane. His comedy excels in moments of awkward confrontation. Witness the conclusion of an otherwise uneventful cab ride:

" 'They should all be deported,' said the taxi driver as they drew to a halt.

" 'Er, who should?' said Richard, who realized he hadn't been listening to a word the driver said.

" 'Er -- ' said the driver, who suddenly realized he hadn't been listening either -- 'er, the whole lot of them. Get rid of the whole bloody lot, that's what I say. And their bloody newts.' "

These moments, albeit plentiful, are not sufficient to carry the day. Missing are the outrageous characterizations that charmed the "Hitchhiker" books; indeed, save for the quirky Dirk himself, Adams' cast is a wan and almost antiseptic assortment sent over by Central Casting -- from an absent-minded professor to a spoiled son of wealth. But the real downfall of "Dirk Gently's Holistic Detective Agency" is its serial mentality: Once its single gimmick is revealed, Adams' barest-boned plot serves little more than as groundwork for the inevitable series of sequels.

And, of course, the final page reads: " ... to be continued."

For Douglas Adams, Dirk Gently is one step forward and two steps back. For his fans, and only his fans, is it recommended.

The reviewer, a Washington attorney, is the author of "Stephen King: The Art of Darkness" and editor of "Prime Evil," a forthcoming collection of contemporary horror stories.