The journalist who writes out of devotion to an idea -- not a political program but a philosophical conceit -- is a rare animal. There are journalists who cover the world of ideas, which is to say they report on the lives and work of people who have them. There are scholarly essayists and social critics who write for magazines, but it's hard to imagine them engaged in the daily labor of reporting. For the most part, the obsessive working and reworking of an intellectual theme is not the business of journalists, which is why, though you can speak with a straight face of a "novel of ideas," a "journalism of ideas" is almost a nonsense phrase.

Janet Malcolm has long been an exception to this rule -- in our time, maybe the exception to it. Over the course of six, now seven, rigorously intelligent books and countless articles for The New Yorker, she has again and again returned to one theme: the vexed relationship between objective truth and the narrative truth we impose on it. Stories -- those told by journalists and biographers, lawyers and witnesses, analysts and patients -- are always a violation of objective truth, even if they contain no overt lies. And yet we are dependent on them, because the raw truth -- what really happened -- is messy, incoherent, unsatisfying, often boring. The betrayals and losses inherent in the imposition of narrative -- and the power struggles over who will impose it -- are Malcolm's great subject, her wellspring.

So, for example, "The Silent Woman" is a meditation on the competing story lines about Sylvia Plath -- those advanced by feminist critics who see her as a martyr and that advanced by her husband, Ted Hughes, who guarded his version of her mostly through reticence. Many of Malcolm's writings about psychoanalysis spin out the idea that at its best, analysis seeks to free us from the incessant need to make our lives conform to a recognizable plot line. Even "The Journalist and the Murderer," which is mainly concerned with the built-in duplicity of journalism, draws on this larger theme. The duplicity lies in the fact that a journalist can never tell another person's story exactly as that person would want it told, but promises, implicitly or explicitly, that he can. Malcolm's unwavering awareness of such difficulties gives her work a tragicomic tone that is more European than American, more philosophical than journalistic. And yet she has remained a working reporter, searching out sources, stockpiling facts, telling stories -- albeit with a wry self-consciousness about the epistemological confines of her trade.

Malcolm's newest book, "The Crime of Sheila McGough," is in many ways the most trenchant statement yet of this theme. But the story in which it is embedded is the least prepossessing. The neighborhood is a little drab -- no poets, no murderers, no Freud.

Sheila McGough first snagged Malcolm's attention with an unpromising device. She wrote her a letter -- the sort journalists get all the time -- saying that she had been the victim of a miscarriage of justice. McGough's letter contained some of the details of her case -- she was a defense lawyer; she had been convicted of a crime she did not commit -- but what jumped out at Malcolm was that her correspondent, whom she had never met or heard of, had put the word framed in quotes, as in "The U.S. Government office in Alexandria 'framed' me," suggesting, perhaps, a rhetorical self-consciousness not unlike Malcolm's own. As a clue to McGough's character, however, these quotation marks were to prove entirely misleading. For McGough sincerely believed she had been framed, and she was, as it turned out, the least ironic and artful of narrators.

When she wrote to Malcolm, in the winter of 1996, McGough was 54 years old and living, as she had all her life, in Alexandria, Va. She had been disbarred and had served two years in prison for what the prosecutors called an "escrow scam" in which, they said, she had colluded with one of her clients, a genial, indefatigable con man named Bob Bailes. (The precise charges hinged on a complicated and rather dull scheme involving the purchase of dubious insurance companies. Suffice it to say that McGough at one point agreed to hold in her own bank account a large sum of money Bailes told her belonged to him, but that, strictly or even loosely speaking, did not.)

Talking with McGough and "poking and peering" into every aspect of her case, Malcolm soon decided that she was innocent. But while McGough saw herself as the victim of a Government frame-up, Malcolm saw her as the victim of something at once simpler and more mysterious: her own "preternatural honesty and decency." What this meant was that McGough never gave up on Bailes. After he had gone to prison, yet again, for fraud, she continued to fight for him "as if nothing had happened . . . as if he were Alfred Dreyfus, instead of the small-time con man, with an unfortunate medical history and an interesting imagination, that he was."

McGough had never married; she had no children; she lived with her parents. Law was a second career for her, and she took it up like a calling, with a purity of purpose, a single-mindedness that struck others in her new profession as naive or suspect. To keep filing appeals for the incorrigible Bailes, to speak respectfully of his "businesses," to refuse to speak about him at all until after his death (McGough did not testify in her own defense because she feared that in a cross-examination she would harm him with her answers), she would have to have been in love with the guy or in cahoots with him, they figured. Yet Malcolm persuades us that McGough was neither. "The crime that Sheila McGough was convicted of in 1990 was the crime of not letting go," she writes, "of not accepting the unwritten law of closure," which despite the possibility of appeals is a necessary fact of the legal system, a safeguard against "an endless round of rematches." Bailes had employed other lawyers in his time -- Malcolm gamely interviews all of them -- and they regarded him with a certain bemused tolerance, but none of them thought he had been "wronged."

Yet if blinkered loyalty was McGough's crime, then her inability to convince her colleagues she was innocent of anything more serious was the function of another peculiar aspect of her character. McGough told the truth, but she couldn't tell a good story. Her speech was "guileless and incontinent." When Malcolm first met with her, McGough, "who looked and sounded like one of the blandly wholesome heroines of 50's movies," talked "almost uninterruptedly" for two hours. Yet she was "not interested in telling a plausible and persuasive and interesting story. She was out for the bigger game of imparting a great number of wholly accurate and numbingly boring facts."

Out of this sludge of detail, Malcolm concocts a narrative that she and we find plausible, mostly because she builds a convincing case for the singularity and integrity of McGough's character. But McGough's lawyers were unable to do the same. While the prosecutor in her trial had a coherent story to tell -- namely that a greedy lawyer had crossed that tempting line between defending a con man and collaborating with him -- McGough had only the (apparent) truth: that she had held Bailes's money without realizing that it actually belonged to hoodwinked investors because she believed in a principled way in accommodating her clients. And true or not, this lacked the ring of truth.

Sheila McGough's story is a slender one -- its intrinsic dramas are on a small scale -- and there are times when the rhetorical burden Malcolm asks it to bear seems a little heavy. Yet it is wonderful to see Malcolm turn her full attention to a criminal proceeding, for here is a setting where the ability to arrange the loose tiles of memory into a coherent pattern has the most bluntly practical of consequences. It's not quite fair to say, as Malcolm seems to, that in a courtroom the best story always wins. Sometimes a defense lawyer can triumph without even trying to construct an alternative scenario in which his client did not do it. He can chip strategically at evidentiary weaknesses in the prosecution's story or appeal to a jury's fears and biases in a much more direct way -- think of the O. J. Simpson trial.

Indeed, as Malcolm points out, he can also discredit a witness who tells too good a story, who obeys the normal laws of human discourse -- editing, eliding, fashioning the random flow of events into a tidy narrative. In the general run of human conversation, we require and reward such skills. But in a courtroom, a witness who tells too coherent a story is probably leaving something out -- not telling "the truth, the whole truth and nothing but the truth." Like the law itself, Malcolm's work thrives on such paradoxes. And, as "The Crime of Sheila McGough" reminds us, no other writer tells better stories about the perpetual, the unwinnable, battle between narrative and truth.