Implications Of Apocalypse < THE THANATOS SYNDROME by Walker Percy; Farrar, Straus & Giroux; 372 pages; $17.95

By Paul Gray

Three of Author Walker Percy's five previous novels bear titles with implications of apocalypse: The Last Gentleman, Love in the Ruins and The Second Coming. The other two, The Moviegoer and Lancelot, are exceptions in name only. For all of Percy's fiction revolves around a central question: can humane, civilized life survive this murderous, mechanized century? Details change from book to book, but a number of constants recur. The hero is typically a Southerner and a loner, a weirdo in the eyes of friends and relatives, whose despair at the decline of civilization has lured him into alcoholism, drug addiction or rampant crankiness. His struggle back toward health and sanity is usually undertaken with the help of a younger woman, who may be as wounded a victim of modern life as he. The saving grace is just that: a recognition that Christian, specifically Roman Catholic, teachings can still offer hope to lost souls. And the setting tends to be Louisiana, where Percy, 70, has spent most of his adult life.

That, in essence, is the plot of The Thanatos Syndrome, but Percy has done more here than simply repeat himself. The theme may be familiar, but the variations decidedly are not. For one thing, this novel embodies Percy's most detailed, explicit attack on contemporary materialism and science. For another, the philosophical warfare has been artfully disguised as a thriller.

The time is the mid-1990s, and Dr. Tom More has returned home to Feliciana parish, that swath of Louisiana land running "from the Mississippi to the Pearl, from the thirty-first parallel to the Crayola blue of Lake Pontchartrain." More (a prominent, visionary presence in Love in the Ruins) has spent two years in a minimum-security federal prison in Alabama for peddling uppers and downers. "I needed the money," he tells the two physician friends who have been charged with overseeing his probation. Now Tom, alcoholism temporarily in control, needs to resume his psychiatric practice. The trouble is, no one in Feliciana seems to require the old- fashioned Freudian counseling he has to offer.

The former patients he manages to see behave strangely: "In each there has occurred a sloughing away of the old terrors, worries, rages, a shedding of guilt like last year's snakeskin, and in its place is a mild fond vacancy, a species of unfocused animal good spirits." Among the victims of this odd malady is Tom's second wife Ellen, who in his enforced absence has become a star on the tournament bridge circuit. She has developed the ability to compute exactly the location of all cards in the hands of her partner and opponents. She speaks in two-word sentences and flaunts herself sexually like a pongid. The baffled shrink wonders, "In a word, what's going on here?"

The pages Percy devotes to establishing and then fleshing out this mystery are as gripping as any he has ever written. Dr. More's slow piecing together of unsettling symptoms proceeds with nightmarish fascination. Any solution to such a carefully rendered enigma is likely to seem a letdown, and Percy's answer threatens, for a time, to stop The Thanatos Syndrome dead in its tracks. Tom, aided by his young, distant and potentially kissing cousin Lucy Lipscomb, herself a doctor and an epidemiologist, discovers that the local water supply is being laced with heavy sodium from the coolant of a nearby nuclear power plant. Whodunit? Not, it turns out, the National Institutes of Health or the Nuclear Regulatory Commission. The villains are a couple of doctors, both known to Tom, who have contrived on their own to salvage the "American social fabric" by doping the local populace.

The next step seems simple and predictable enough. All Tom More has to do is challenge the perpetrators and put an end to their nefarious plot. That is the way that Robert Ludlum or Jack Higgins would wrap up such a story, and Walker Percy scrupulously delivers all the promises his plot provides. But that is not all. For while More is trying to pull the plug on the doctored water, he must also ponder a vexing question. What is wrong, after all, with a simple process, akin to fluoridation, that makes people happier than in their natural state and that dramatically reduces crime and social pathologies? Are Dr. More's spaced-out patients better now than when he treated them for the normal run of human miseries? A mastermind of the sodium conspiracy taunts him, "You can't give me one good reason why what I am doing is wrong."

Not one good reason, perhaps, but many implicit ones, and all present in the language of this novel. The time is coming, Percy insists through his hero, when people can choose to be less than themselves, through technology, or rediscover their spiritual amplitudes, for good or ill. To be fully conscious, even of the worst, seems preferable. Tom describes a sunfish caught in a local bayou: "The colors will fade in minutes, but for now the fish looks both perfectly alive yet metallic, handwrought in Byzantium and bejeweled beyond price, all the more amazing to have come perfect from the muck." An engineered life would leave no room or tolerance for such perceptions.