To put the matter succinctly, The Da Vinci Code by Dan Brown (Doubleday, $24.95) is overwritten (454 pages), overplotted and overdrawn.

And Christians are likely to find it offensive, although it is exceptionally clever in an intellectual way. It distorts church history while putting a modern dress on the hoary Arian heresy, weaving historical and pseudo-historical threads through a contemporary mystery that is set in motion by the murder in the Louvre of the famous museum's curator.

Brown's novel, his second featuring the Harvard symbologist Robert Langdon, has also been overbought and overpraised, due at least in part to a marketing ploy which found Doubleday distributing 10,000 free advance copies to the media. This, according to The New York Times, was more copies than any of his previous books sold.

On the surface, the tale involves Langdon and a French police cryptologist, Sophie Neveu, in efforts to unravel puzzling clues crafted by Jacques Sauniere, Sophie's grandfather, as his life ebbed away after he was shot by a monkish albino figure pursuing a religious secret of which Sauniere was the last surviving guardian. Three other guardians were killed earlier.

Because Langdon's name surfaces in Sauniere's cipher, he immediately becomes the chief suspect, making it necessary for him, with Sophie as an ally, to evade the police while following the clues. Which, of course, are also of interest to the killers because Sauniere, before his death, sent them down a blind alley.

As you might expect, however, nothing is as it seems. Sauniere, it turns out, is the head of a secret society, the Priory of Sion, dedicated to protecting historical documents challenging the divinity of Jesus. Moreover, the monkish figure is a member of Opus Dei acting on behalf of the bishop who heads that society. Behind them both is a shadowy character they know only as the Teacher.

(This is apparently open season on Opus Dei. The leadership of the church society was also portrayed as murderous in the recent spy tale, "The Confessor.")

Back to Sauniere. His clues pinpoint the location of the documents. They refer the cognoscenti to famous Leonardo da Vinci paintings at the Louvre, among them the Mona Lisa and the Last Supper, in which other clues regarding the nature of the secret are to be found, thus explaining the title of Brown's book.

Now if you have strong feelings about reviews that give away too many details of a mystery (it is in the details, after all, that a mystery achieves the status of a mystery), then you had best stop here and go on about your business.

Brown's secret concerns the Holy Grail.

However, the Holy Grail is not the chalice of the Crusades and Arthurian legend but the "cup," or womb, of Mary Magdalene.

As Brown has Langdon explain to Sophie, in da Vinci's rendition of the last supper the Magdalene is the figure generally thought of as an Apostle resting on the breast of Jesus. She is doing so because Jesus, who is a great man but nevertheless only a man like other men, is her husband.

Plunging further into the land of make-believe, "The Da Vinci Code" then identifies Sophie as a blood descendant of that union, this too being among the secrets Sauniere had been guarding, even keeping this knowledge from Sophie.

Moreover, all of this, including a "spiritual" sex ritual which led Sophie to shun her grandfather for 10 years, is tied up with the church's suppression of the "sacred feminine" side of Christianity. One aspect of this suppression was the manipulation of Scripture by the early church, with contrary writings being left out of the scriptural canon.

Through his characters, Brown also posits this suppression as a factor in the development of attitudes which led to the killing of 5 million women during the Inquisition.

One can argue, of course, that in fiction the author has great interpretive leeway. As indeed he does. But Brown mixes actual -- if arcane -- facts with speculation and fantasy in such a fashion that the whole easily takes on that aura of historicity.

To a writer, this is a skill of great value. But, like any skill, it can be put to less-than-honest use. In "The Da Vinci Code" it is used to call into question the basis of Christian faith and to attack the church in a format -- the novel -- where one does not ordinarily expect to encounter argument masquerading as historical truth.