In Murdoch Country, the Gods Wear Tweed : THE MESSAGE TO THE PLANET <i> by Iris Murdoch (Viking: $22.95; 563 pp.) </i>

The ground in Iris Murdoch’s novels perpetually shifts beneath us. At one moment, her clutch of assorted English intellectuals and artistic types are engaged in perfectly ordinary exercises of speculation, lust, ambition, greed and depressiveness. At the next, an aura of the supernatural falls upon them, as if the old gods were alive and wore cardigans and good shoes.

These characters are commonplace if snobbish, clever if long-winded, we think; and then, suddenly: No, they are quicker and more spectral than life. The humdrum declares itself magic, and the magic promptly declares itself humdrum. As in a roller-coaster--often with the same sense of being lifted out of our own gravity--we never quite know where we are. Except, and unmistakably, in Murdoch country.

Her painters, lawyers, academics, failed clergymen, musicians and writers tend to be on the verges of middle age. They are uneasy or morose and, despite their talents and comforts, subject to an acedia close to spiritual death. Their women seem subdued, but they are accumulators of the electricity that builds up in the oppressive air, and they can flash out like lightning.

Into this uneasy stasis moves a guru-like figure, a man of enigmatic intellectual and moral force, an enchanter. He provokes thunder storms, displacements, violence, wild leaps, odd changes; and by the time the book ends, at least some of these high-strung people will find themselves upended. It is a kind of conversion: Like so many New Testament Sauls, they are knocked off their mounts, though when they re-mount, they usually find themselves not St. Pauls, but Sauls still.

“The Message to the Planet” follows the pattern. Marcus Vallar was a mathematical prodigy, then a painter, then a linguist searching for the roots of a universal language. He fascinated and unsettled those he met. Vallar alternately helped and quarreled with Jack, whose brilliant painting career he inspired. His corrosive questioning led Gildas to lose his faith and quit the priesthood. He made an ardent disciple out of Ludens, a scholar, only to savage him and drive him away. He put a curse on Patrick, an Irish poet. And then he disappeared.

When the book starts, years later, Patrick is dying of a mysterious disease. Jack, Gildas and Ludens speculate that Vallar’s curse may be responsible. Ludens, still worshipful, searches and finds him living in a country cottage, aged, paranoid and scribbling what Ludens is certain must be a mighty though obscure philosophical work.

Ludens brings Vallar back to London along with the latter’s Gypsy-like daughter, Irina. Vallar climbs into bed with Patrick and embraces him. It is a comically awkward scene; Vallar seems half-hearted and fumbling about it, almost as if he didn’t really know what to do and were simply humoring Ludens. Yet Patrick promptly recovers.

The heart of the book concerns Ludens’ effort to be disciple to a figure he has decided is somewhere between Spinoza and Christ. Murdoch leaves it open as to whether Vallar is an authentic magus or a burnt-out, half-mad old man. Ludens’ need to find a master endows Vallar with a prophetic glow, one that includes Irina, with whom he falls loftily in love.

To him, she is the magician’s daughter, and touched with his magic. In fact--or almost fact, granting Murdoch her ambiguities--she regards her father as “barmy.” She places him in an expensive sanitarium in the countryside, takes care of him in a cottage on the grounds, and waits for him to die so she can go off and have fun.

Ludens’ need to believe makes his attendance upon Vallar a quixotic quest that is both goofy and deadly serious. He brings notebooks and an expensive fountain-pen; he asks the old man whole lists of philosophical questions, all in an effort to get the great work out. He takes Vallar’s resistance, his quirks and oddities, as signs of inspiration. And he is overwhelmed and shoved aside when a band of New Age pilgrims, on their way to Stonehenge, invades the sanitarium and camps outside the cottage, waiting for revelations by charisma instead of by the book.

Comedy entangled in mystery, fraud indistinguishable from saintliness are the elements of this, as of previous Murdoch conundrums. Jack comes down to visit, along with his wife and mistress, both of whom live in the same house with him and battle each other in highly arcane fashion. So do Gildas, Patrick, a rabbi, a priest, and other assorted characters. Each works upon his or her entirely tangential obsessions. A tangency that doesn’t quite touch is Murdoch’s pattern of people’s relations to each other and to the universe. Across the infinitesimal gap, her sparks fly.

If “Message” has the complexity, the wonderfully unexpected talk, the fey and jarring balances and imbalances of Murdoch’s other recent novels, it is something of a falling-off. Energy is lacking. There is lethargy in it despite the wit. The characters say interesting things, but they are not particularly interesting or distinctive in themselves. The enchanter figure, this time, is more vague than exciting.

But as always, Murdoch’s itchy intellectual seekers and slobs create a world that is entirely artificial and yet infinitely inhabitable. It draws us in, and when we finish one of her books, we miss it. Each new book resembles the others, and yet a Murdoch fan is glad to be back.

It’s rather like being a Wodehouse fan. You know everybody. And a Murdoch enchanter, to tell the truth, is a kind of Jeeves. Her highbrow Bertie Woosters, having made a terrible mess of things and flapping out of control, are hopelessly stuck. The enchanter arrives, gets them going, and in his drastic and disruptive way, restores a sort of order. He is not as unflappable as Jeeves, but he is as mysterious, as unquestionable, and quite often as funny.