BOOK REVIEW : A Tale of Voyeurism With a Bit of Horror : SLIVER: A Novel, <i> by Ira Levin</i> . Bantam Books, $19.95, 256 pages

There is a hotel in Orange County where you can take a room, get a series of massages, and cross a little bridge to a restaurant that offers perfect ethnic cuisine. (I can’t say what kind of cuisine, that might give away the secret.) It’s a great place to relax, very “Old California.”

But be sure never to check into Room No. 6, or at least moderate your activities if you do. There’s a peephole in Room No. 6, and those nice guys who do the massages supplement their minimum wages and their generous tips with invigorating glimpses through the peephole into Room No. 6.

When tired couples strive mightily to put the romance back into their marriage, they usually manage, as a side effect, to put the punch back into a lot of cheerfully giggling masseurs.

The peephole! The one-way mirror! How those devices have lightened both our everyday lives and all the fiction we’ve ever read. Something that’s excruciatingly dull becomes automatically interesting--if it’s watched. No species is as curious--and as prurient--as the human race.

“Sliver” is about this phenomenon, and since the author has included a not-very-veiled threat to critics who inadvertently give his plot away, let’s see if we can look at “Sliver” without talking about the plot at all.

The place is a “sliver” apartment in the Carnegie Hill District of Manhattan. Someone has torn down a couple of brownstones and put up a tall, slender, state-of-the-art building with only two apartments to each floor. Another place is the Grill Room of the Four Seasons, where writers and editors meet and eat, and Simon & Schuster is referred to as “Essandess,” and “Joni” (Evans) is mentioned in passing.

Kay Norris, a 39-year-old editor with Diadem Books, has decided to move out of her charming but ratty and roach-ridden Village apartment. She’s had two disappointing relationships with know-it-all guys who are older than she is, and she relies now for emotional support on a flock of good friends and a smart cat named Felice.

You know from Page 1 that Kay Norris is being watched, and it’s not through one measly peephole. She’s being watched by a series of carefully hidden TV cameras. This whole building has been bugged by a master voyeur. The phone lines are tapped. The elevators are watched. The laundry is “secured” by cameras.

Every apartment has been wired and rigged. One person watches. He’s hooked on “the soap opera that God watches,” these electronic slivers of life that come to him over his several television monitors.

When this mystery man first sees Kay, he doesn’t want to kill her--although the death rate in this apartment is something fierce. He just wants to look, and look. And pursue some solitary sexual gratification along the line.

Who could this mysterious gentleman be? Could he be Sam Yale, the seedy recovering alcoholic who used to direct TV in its Golden Age? Could it be any one of a number of doormen, some of them with sinister accents, who have access to these bundles of electronic equipment? Or that sweat-stained jogger with the hood concealing his face? Or somebody else?

God knows, the world is full of peculiar people. And any one of us, man or woman, finds it hard to resist the urge to peek, and pry, and snoop.

Mr. Ira Levin? Are you noticing that I haven’t given away one thing about your book? I think I can say that Kay Norris lives such a blameless life, consuming yogurt and running the vacuum cleaner and walking in the park and gabbing on the phone with her friend, that it comes as a refreshing relief when the voyeur insinuates his way into her real life--even though we all know that no good can come of it.

Actually, lots of good comes from it! The dullness of everyday life is transformed into the soap opera that God watches. If we are watched, we must be important! This is not a horrifying fantasy but a comforting one. “Sliver,” on the horror graph, comes in at about the level of a hot fudge sundae. But that doesn’t mean it isn’t fun to read--and lick--and savor.

Next: John Wilkes reviews “Searching for Certainty: What Scientists Can Know About the Future” by John L. Casti (William Morrow and Co.).