WALKER PERCY is arguably the greatest living Southern novelist. His canon is as solid as any contemporary American's, north or south of the Mason-Dixon. The Moviegoer, Percy's first and best novel, received the National Book Award in 1962 and the works that followed--The Last Gentleman, Love in the Ruins, Lancelot, and The Second Coming--established a critical and commercial cult following that was, and is, highly deserved.

The Thanatos Syndrome

By Walker Percy

Farrar, Strauss and Giroux; 372 pp.; $17.95

Where does Percy stand with the release of The Thanatos Syndrome, his newest and least engaging piece of fiction? The writing here is piquant, elegant, well-whittled, and striking. And though the stakes are high--eugenics, AIDS, nuclear waste, and existential terror--one can't help thinking midway through this novel: Percy's all dressed up with no place to go.

The story-line is nifty. Too nifty, maybe, as the characters are upstaged by Percy's plotty pyrotechnics.

To be brief: Dr. Tom More, a psychologist/jailbird on parole for selling drugs, stumbles across a scheme to improve behavior patterns in Feliciana parish. His colleagues have spiked the water-supply with "molar sodium 24," a chemical substance that causes women to lose their sexual inhibitions (they present themselves rearward like primates), heightens children's school performances (verbal and mathematical scores rocket), and even helps to hone More's wife's tournament Bridge game: "This lady knows where the cards are. I don't know how she knows but she knows. I don't think she knows she knows either. It is as if she had a little computer stored in her head...."

PERCY HAS a computer in his head, apparently. More unfolds the water-supply plot with the symmetry and cunning of a Creole Hercule Poirot. But agents more intimidating than Bionic Bridge players lie at the end of the molar-mystery. More discovers a kiddie-porn racket which Percy depicts too graphically for my taste:

In the photograph of Van Dorn dangling the child, the child is shown to have been penetrated but only by Van Dorn's glans and certainly not painfully, because the child, legs kicked up, is looking toward the camera with a demure, even prissy, expression. Her legs are kicking up in pleasure.

The idea, of course, is that molar sodium 24 has zonked out both pedophiliac and pedophiliee to such a degree that they have become numb, orgiastically numb, to the horror of their situation.

Percy extends the metaphor to man. We all drink the water. We're all zonked out on our separate somas. But Percy's kiddie-porn portrait shocks without edifying. The metaphor, a valid one, is too sensationally packaged. Why stoop to conquer? Why exploit to elevate? Percy's better than this. And so are we.

The sheer discursiveness of The Thanatos Syndrome lends itself to all manner of loose, didactic, free-associative diatribe. We're so swept up by the movement of the novel--and this novel does move; it has a wonderful clip--that we find ourselves swallowing pop-philosophical placebos, medicines Percy, a physician, might have prescribed better elsewhere.

When Percy hops on the Apocalypse Express at the novel's conclusion, it's invigorating writing. But it seems out of place:

Do you know why this century has such terrible events happen? The Turks killing two million Armenians, the Holocaust, Hitler killing most of the Jews in Europe, Stalin killing fifteen million Ukrainians, nuclear destruction unleashed, the final war apparently inevitable? It is because God agreed to let the Great Prince Satan have his way with men for a hundred years--this one hundred years, the twentieth century.

Isn't that special?

PERCY HAS been called "our cool Dostoevsky," and the worst thing The Thanatos Syndrome reveals about him, I think, is that he isn't half as "cool" as he once was. That moniker's an oxymoron, by the way. Dostoevsky was never "cool"; his passion propelled him. But it's precisely Percy's understated anger that makes his prose, at its very best, bristle. There's a quiet, marvelous moment at the end of The Thanatos Syndrome where the angst of our condition comes pouring through:

During the minute or so of happy talk at the end of the newscast, when other members of News Team-7 are smiling and making pleasantries and semi-jokes as they stack their papers, Chandra will have none of it: no grins, no banters. Instead, she often challenges the anchorman: "What you talking about, have a nice day--what's nice about that?"--socking the weather map with her pointer.

The forecast isn't getting any better--that's what The Thanatos Syndrome would have us believe.

Somebody. Quick. Give Mr. Percy back his pointer.