ASYLUM.<i> By Patrick McGrath</i> .<i> Random House: 254 pp., $22</i>

Patrick McGrath’s new novel, “Asylum,” is one of those rare pleasures, a book as absorbing as it is intelligent--a book so rewarding to read that I found myself spacing out chapters, restraining my curiosity to savor the elegant sentences. Those readers who know McGrath’s acclaimed earlier work (including three novels, “The Grotesque,” “Spider” and “Dr. Haggard’s Disease,” and a collection of short fiction, “Blood and Water and Other Tales”) will probably expect no less from this writer. His fictional worlds are vivid yet mysterious; his characters are endlessly fascinating.

“Now hell is decidedly on Earth, located within the vaults and chambers of our own minds.” I quote this sentence from an introduction McGrath wrote with Bradford Morrow for the anthology they co-edited, “The New Gothic.” Morrow and McGrath suggest that contemporary writers have been forced by the ugly history of this century to turn away from the metaphors of 19th century Gothic fiction, from architecture and furniture to a new interior, the human psyche. McGrath keeps coming back to this interior in his novels. The anatomy of the mind is his subject, and he is an expert at nuance and detail.

At the beginning, “Asylum” pretends to be little more than a lecture delivered by an eminent psychiatrist to his colleagues. The narrator, Peter Cleaves, is a forensic psychiatrist at a maximum-security mental hospital in rural England, and he introduces the story with the clinical jargon of his profession. About the evolution of the love affair that is his subject, he writes, “Recognition. Identification. Assignation. Structure. Complication. And so on.” This is the plot of the book in a nutshell. Of course, there’s a satiric edge to the language here, and the shell quickly splits apart: “Stella Raphael’s story,” the narrator continues, “is one of the saddest I know.”

So we plunge into this sad story, this psychological hell, led by our capable Cleave. Stella is the wife of psychiatrist on the staff at the hospital, Dr. Max Raphael, whom the narrator describes as “a reserved, rather melancholy man, a competent administrator but weak; he lacked imagination.” Stella is a modern Emma Bovary, a stylish, beautiful woman who sucks on her cigarettes and wanders listlessly around the grounds of the hospital. One day, she goes into the vegetable garden to pick some lettuce and finds her young son talking to one of the parole patients, an artist named Edgar Stark. Edgar has been commissioned by Stella’s husband to rebuild an old Victorian conservatory. Stella is intrigued by the man and admires, in particular, his hands, “good hands . . . long, slender, delicate hands.”

With those same good hands, the hands of a sculptor, Edgar had murdered his first wife. And not just murdered her. He had cut off her head, mounted it on a podium and treated it as a chunk of clay, gouging out the eyes, hacking at the flesh to reshape it into a work of art.

Stella and Edgar meet again in the garden and later at a hospital dance. She falls in love with him. What follows through the rest of the novel is the slow, relentless deterioration of love into madness or, as Cleave would say when he’s in his clinical mode, the progression of recognition into complication.

Edgar is a familiar type in fiction--the shabby, handsome, erotic, dangerous man who lures women toward disaster. And as this doomed love intensifies, the novel skirts perilously close to melodrama. Describing Stella’s attraction to Edgar, McGrath writes: “She saw him as her charming rogue. . . . She couldn’t oppose him at all, it wasn’t possible, for she had begun to surrender herself and no longer felt distinct and separate from him, rather that she was incomplete without him. She understood what was happening, she was falling in love, and she didn’t want to stop it.” I suspect that McGrath is deliberately contrasting two extremes of language, the melodramatic and the scientific, to show us how difficult it is to comprehend extreme emotions.

“Asylum” succeeds brilliantly at the task of probing, as the narrator says in a reference to Stella, “the obscure regions of her psyche.” The story of this love affair unfolds like a dream into a nightmare--the characters move relentlessly toward their tragic ends, with desire raging like a fire, gathering strength and destroying everything and everyone in its path.

This is a thrilling book to read if only for its plot. Every page is full of portent, of mystery, of the suggestion of the disasters that are about to occur. But there is an even greater thrill: the thrill of insight.

When Max Raphael looks at his guilty wife after having learned that she’s in love with Edgar Stark, he doesn’t feel a simple anger. Nothing is simple in this fiction. Instead, “Max couldn’t quite believe that she wasn’t crawling about on her hands and knees, weeping and tearing her hair out and begging his forgiveness. He was aghast with a sort of furtive pleasure that she didn’t behave with shame, which made her in his eyes more shameful still, and so compounded his sick delight in the whole sordid performance.” The identification and exploration of such passionate ambivalence becomes in itself a suspenseful journey, one that rewards us at the end with a deep understanding of these characters.

Perhaps the name of the destructive and self-destructive lover--Edgar--is a subtle reference to that other tortured, shaggy artist, Edgar Allen Poe, who was so unflagging in his inquiry into the nature of obsession. McGrath is just as unflagging. With great sympathy and wisdom, he explores those obscure regions of the psyche where love and evil mingle, where tragedy has its roots.