By Gary Devon

Random House. 326 pp. $18.95

GARY DEVON'S second novel -- his first was Lost, a well-received "novel of terror" -- is accompanied by a cantata of promotional prose in which scarcely a stop goes unpulled. Devon is "a master of mind-bending plot twists and heart-pounding tension" who has written in Bad Desire "a bravura tour de force of erotic obsession and murder" that culminates "in a climax as stunning and unpredictable as the best of Hitchcock." All in all, "a masterpiece of dark passions and unrelenting suspense."

All of which doubtless makes Gary Devon feel good, but none of which bears much resemblance to the truth. Bad Desire isn't a bad novel, indeed in some respects is a rather good one, but it's approximately as mind-bending and heart-pounding as a placid day on a summer beach -- so it's all the more a pity that the novel's publication was delayed by several weeks, making it unavailable for seaside reading in the summer of 1990.

Bad Desire is if anything the quintessential beach book, which is neither a compliment nor an insult but a simple statement of fact. Readers lazing under the summer sun don't want books that bend their minds and pound their hearts; they want amiable entertainments that can be picked up and put down every few pages with no sense of urgency. I read it in conditions comparable to those at the beach -- an enervating head-and-chest cold that induced a powerful urge to snooze -- and I found it just about perfect: I drifted in and out of my little naps without once feeling that I was being unfaithful to something more important than these recuperative slumbers.

Which is why books are so much better for vacations and minor illnesses than broadcasts or videotapes. If you're listening to and/or watching the latter, you tumble gently asleep and then awake to the jarring realization that you've missed something -- a patch of radio music or chatter now vanished forever into the ether, or a stretch of videotape you'll have to painstakingly retrace. But when it comes to a good old book, you just struggle back into consciousness, grope for your book in the sand or on the bedcovers, prop open your eyelids, and pick up where you left off.

The books that work best in these circumstances are those that pique your curiosity without ever engaging your emotions: You want to be interested enough to keep on to the end, but not so involved that reading becomes more important than sleeping. Bad Desire fills that particular bill to perfection. Within a few pages Gary Devon has you wondering whether, and if so how, Henry Lee Slater will be able to rub out the interfering grandmother of Sheila Bonner, the teenaged heart-throb with whom he's become obsessed, and wondering furthermore what complications will ensue; but your interest is more academic than emotional, and if Wynken, Blynken and Nod drop by for a visit, well, Henry and Sheila can just wait until they leave.

Henry is 43 years old and the mayor of Rio Del Palmos, an "exclusive community" of 59,000 souls somewhere on the Pacific coast near Los Angeles. He is a smoothly charismatic figure with (unspecified) political ambitions and a presentable wife named Faith whom he no longer loves and, we soon discover, a throbbing passion for Sheila, who is 17 and beginning to nurse her own brood of longings and lusts. So far Henry has restricted himself to giving Sheila little tokens of affection and winning chaste kisses from her in exchange; but he has greater, or baser, hopes and is determined to fulfill them.

This means getting rid of Granny, the dear cranky little old New England Yankee with whom Sheila lives. Granny is on to Henry's dirty little secret and is determined to head him off before he has his vile way with her ward, so Henry contracts with a hired gun to do the old girl in; he is, as the promotional copy has it, in the grips of "a frenzied passion that drives him inexorably to murder," as well as to enough related developments to keep Devon's plot gurgling along until its appointed end.

These, in no particular order of importance or interest, are the questions that arouse the reader's mild, lazy curiosity: Will the hired killer do his job? Will Henry and Sheila find their way to their bed of shame? Will Faith discover Henry's treachery? Will the trail of clues lead in time not merely to the murderer but to his employer? Will further murder be necessary, not to mention unmitigated horror? Will justice at last be done? NO, YOU'RE not going to get the answers here. You'll have to go to the beach, or get a bad cold, or wait for the paperback and read the book between subway stops: I'm not telling, except to say that Devon puts a nice twist on matters at the end -- not a surprising twist, just a nice one -- and manages to give each of his characters something close to his or her just desserts. He isn't exactly the most riveting prose stylist -- early on he slips into breathy portentousness, and only rarely escapes from it thereafter -- but he's competent at worst and amusing at best. His publicists' claims to the contrary notwithstanding, his characters are neither "unforgettable" nor "sharply etched," but they stick in the mind long enough to outlast a nap or a swim or some other diversion, and you're more pleased to return to their company than at first you might expect.

All of which is to say that Bad Desire may be trash fiction, but it isn't trashy. Mostly it chugs comfortably along within the confines of its various formulas, but from time to time its characters are truer to themselves than to convention, which in this genre is a certifiable switch: Nothing startling enough to keep you awake, of course, but then isn't that the point?