Two More-or-Less Mystery Novels

EXACTLY what constitutes a mystery novel is something of a mystery to many people. A book can involve suspense, secrets, even a crime, without being a bona fide mystery. This, perhaps, is why the accomplished British mystery writer Ruth Rendell has chosen to publish some of her recent novels under the name of Barbara Vine. Although these novels contain elements of mystery, they also represent an attempt to explore a terrain just beyond the borders of the genre. (She's still going strong as Ruth Rendell, with a new mystery, "The Crocodile Bird," under her old name due out this October).

"Anna's Book," Rendell's latest effort as Barbara Vine, is about a daughter's search for the identity of her birth mother. The daughter's compulsion to discover her biological roots comes close to poisoning the wellsprings of a normal and happy life.

Anna of "Anna's Book" is Anna Westerby, who comes to London from her native Denmark in the early years of this century. Her husband, Rasmus, is frequently away on business, leaving her alone in the unfriendly city with her two small sons. As the story opens, Anna is awaiting the birth of another child, who she desperately hopes will be a girl.

With no one to confide in, but plenty of powerful feelings and sharp thoughts to express, Anna begins a diary. Excerpts from this private record, kept for 60 years, are the strongest and most evocative parts of this novel. Anna's bluntness, naivete, raw intelligence, and flair for storytelling make her a spellbinding narrator.

"I'm proud of her," writes Anna of her newborn daughter, Swanny, "I love her. I like writing that down because a few weeks ago, if anyone had asked me ... I'd have said I don't love anyone in the world.... I thought I'd love my husband when I married him but that didn't last five minutes.... I get worried about the boys ... but I don't care about being with them. The truth is, they bore me. You can't call that loving."

Never in a million years would Anna have dreamed anyone would read her words, but after her death, Swanny, by this time a handsome matron in her 60s, discovers her mother's notebooks and has them translated from the Danish. The diaries become bestsellers - and are even made into a hit television series. But Swanny's serene and pleasant life is increasingly clouded by the doubts sown in her mind by a poison-pen letter alleging that she is not really her mother's daughter. Not until Anna's grandchild - and

Swanny's niece - Ann Eastbrook takes up the investigation of the family's hidden past does the secret of Swanny's origins finally come to light.

The fascination of this novel lies less in discovering the truth about Swanny's birth (although there are many intriguing twists en route to the final disclosure) than in watching the characters of three generations acquiring their distinctive personalities. Whatever surprises the author has in store for us - and there are quite a few - the characters and their relationships remain believably consistent, and constantly believable. "Anna's Book" is a powerful story about two equally powerful needs: the bo undless need to love and the insatiable need to know.

"I felt no curiosity," declares the narrator of Salvatore Mannuzzu's novel "Procedura," a magistrate from the mainland assigned to investigate the sudden death of a colleague on the Italian island of Sardinia.

Judge Valerio Garau died after washing down some pills with a cup of coffee while chatting with his mistress at a local cafe. The capsules contained cyanide. But who put it there and why?

The visiting magistrate has no idea and is not very keen to find out. The deceased judge - described as a witty, charming, cultivated man, something of a Don Juan - has few real enemies. His ex-wife, Niki, seems a bit odd, disappointed in her marriage, still in love with her former spouse, but with no reason at this late date to have wanted to kill him. Lauretta, the mistress - also a magistrate - has known and loved Garau since childhood. Her husband, another judge, has long tolerated his wife's liaison .

The narrator conducts his inquiry in somewhat lackadaisical fashion: His superiors have warned him not to tread on too many local toes, and he is all too willing to oblige. Still, for all that no one seems unduly eager to find the killer, there is pressure to at least go through the appropriate procedures. And in the course of doing so, the investigator eventually makes some surprising discoveries that illuminate the mystery of Garau's life and his death, but are otherwise almost totally without repercus sions. As the narrator aptly comments, "the game is always - and only - its wrappings...."

The setting for "Procedura," which won Italy's Viareggio Prize for fiction in 1989, is Italy in the spring of 1978: The infamous kidnapping and murder of former Italian Premier Aldo Moro hovers in the background. There is an aura of weariness and resignation in the air, a sense that even if the hidden labyrinths of motive, and cause and effect could be untangled, the best thing to do about the case would be leave it behind and get on with "ordinary" life.

Mannuzzu - himself an ex-magistrate and former member of the Italian Parliament - has written what amounts to an anti-detection detective story, suffused with a melancholy, elegant, civilized, yet cynical fatalism.