An ancient and interesting suggestion lies at the heart of David Plante’s new novel, “ABC” (Pantheon, 250 pages, $23): The letters of the alphabet, the ordinary letters in which both this novel and this review have been written, can themselves be objects of mystical contemplation. Understand the alphabet, Mr. Plante suggests, and one can understand everything. And why not? Letters, though finite in number, represent the infinitude of things.

But just how is one to go about understanding the alphabet’s message?

Mr. Plante has a scheme in mind. The original alphabet, he proposes, from which all Indo-European scripts are derived, consisted of a series of pictograms, much like Chinese characters. The primitive letter “A,” for example, might once have represented an ox head, and the letter “B,” a house. (Mr. Plante never makes these derivations clear.) Sometimes a collection of objects, if ordered properly, can convey a meaning, distinct from the objects themselves.

Mr. Plante invents a world of characters who, motivated by the overwhelming urgency of escaping desperate grief, become obsessed with finding meaning in the collection of objects that constitute the alphabet. Such meaning, Mr. Plante suggests, would be tantamount to finding the meaning of everything.

“ABC” begins with Gerard, a professor of French, his wife Peggy, and young son Harry canoeing on a New England lake. They stop to investigate an abandoned house. Unlikely catastrophe strikes: Harry falls through the floorboards of the house and dies. Moments before Harry’s death, Gerard finds a sheet of paper with the letters of the Sanskrit alphabet.

In the weeks following his son’s death, Gerard fixates on the Sanskrit letters. The father does seem very sad about his son’s death — he mopes around the house and howls and cries — and in such a character, obsessive thoughts seem natural enough.

What has begun as a quiet, realistic chronicle of death, grief, and perhaps redemption, however, takes a decidedly weird turn. By chance, Gerard meets another grief-stricken parent devoted to the alphabet — a Chinese woman, Catherine, whose daughter died in a drug overdose. Together, the two travel to London, where they meet up with a third obsessive, David, a Greek whose wife was murdered by terrorists.

The middle third of the book consists of a series of very long discourses by a Cambridge don to this unlikely trio on the history and nature of the alphabet. This portion of the book is vaguely reminiscent of “The Da Vinci Code” in its pedagogical enthusiasms, but without Dan Brown’s intense forward momentum: We learn a great deal about the history of the alphabet and the meaning of the letters of the alphabet, and there are some quotations from Tacitus and Plato. If the professor’s speeches are perhaps a little long, one can never object to learning something new.

The final third of “ABC” introduces a fourth student, a Chechen refugee. Her descriptions of her ordeals, which in his acknowledgments Mr. Plante says were taken “almost word-for-word” from an account in The Observer, form the most effective prose of the entire novel. The foursome heads off to the ruins of Ugarit, Syria, where the novel breaks entirely with the conventions of realism — perhaps necessary to express Gerard’s mystical revelations.

If the central notion of “ABC” is interesting, the novel itself is not. Mr. Plante is not much concerned with compelling plotting — we never learn, for example, just what that Sanskrit alphabet was doing in the abandoned house, nor are we invited much to care. The author forgoes any accurate depiction of the interior lives of his characters and any subtleties in the writing. One example of incompetent prose from a myriad available: “Gerard lifted a juggling ball from the case. It felt solid and heavy, as if weighted to fall rather than to rise.” I’d be curious to know just what, precisely, is weighted to rise. “ABC” is often listless, dull, incomprehensible, and borders at times on the absurdly pretentious.

But Mr. Plante is an experienced novelist — he’s written 12 of them — and one has to imagine that he intentionally chose to write such a novel as this: His characters remark frequently of themselves that they are painfully pretentious, a conclusion with which I can only give my whole-hearted assent.

Pretension is a theme throughout. One character after another is self-conscious of his own pretensions: ” ‘Shouldn’t we laugh?’ Gerard asked. ‘Shouldn’t we be howling with laughter for making pretentious fools of ourselves?'” This suggests that the pretentiousness of the novel is an intentional narrative strategy, the work of a knowing writer — but why a novelist would employ such a strategy, I don’t know.

In a younger and less-experienced novelist, one might suppose that the thing had simply gone astray; in a novelist of Mr. Plante’s experience, the respectful and charitable conclusion is that he has written a difficult novel whose deeper intentions are, at least to this rookie, wholly opaque.

Mr. Berlinski’s first novel, “The Field,” was published by Farrar, Straus and Giroux earlier this year.