Divisadero, by Michael Ondaatje

In his new novel, Michael Ondaatje quotes Nabokov as saying, "Only the rereading counts", which suggests that the book is not intended to surrender its secrets lightly. The same goes for its cast of characters. Only one of them is a professional poker player, but all keep their cards close to their chests. They are intent on not being – to borrow another phrase from Uncle Vlad – "transparent things, through which the past shines". Nabokov goes on to explain that a "thin veneer of immediate reality is spread over natural and artificial matter, and whoever wishes to remain in the now, with the now, on the now, should please not break its tension film". But Ondaatje's characters can't help themselves; the past shines through them like a projector bulb.

One has an apartment on Divisadero in San Francisco. The street was named Divisadero – so the author informs us – either because it was the dividing line between the civilian and military city, or because it provided an excellent vantage-point. It comes as no surprise to discover that the book is – or seems to be – divisible by two. It consists of two discrete stories, and all its characters have fault lines occasioned by irreversible trauma.

The opening story concerns the youth of Anna, Claire and Coop, living on a farm in northern California, just off the Petaluma road. For anyone who knows anything about northern California, Petaluma means but one thing: utopian chicken farmers. These idealists are the subject of a marvellous work of oral history by Kenneth L Kann, Comrades and Chicken Ranchers: the story of a Californian Jewish community. Ondaatje's Petalumanite paterfamilias decides not to join them. Taking possession of his property, he immediately disposes of a thousand laying hens . Dirty realism is not Ondaatje's bag. Blighted romance is more his style.

The farmer's wife dies giving birth to Anna. Claire's mother suffers the same fate in the next bed. There being no father in evidence, Anna finds herself with a ready-made sister. Coop is no blood-brother either, having been adopted four years earlier, when his family was wiped out by a hired hand. So it is not incest when, aged but 16, Anna takes Coop as a lover.

Their arcadian idyll is shattered by Anna's father, come to warn his surrogate son of a freakish ice storm. The lives of Anna and Coop are rent asunder by this double cataclysm. That moment is their divisadero. In later years, Coop becomes a poker player, and Anna a Francophone scholar.

Their stories appear to be leading in different directions. But look again at the names Anna and Coop; observe the architecture of their letters. Do they not belong together, like the strands of a double helix? Perhaps their futures will not be so separate after all (in word, if not in flesh).

Anna's story crosses the Atlantic (the book is also divided between America and France). En route to Dému, last home of the scribe Lucien Segura, in whom she has a scholarly interest, she is introduced (by the light of an arc lamp) to the twisted church spire in the village of Barran. Built in the 13th century, this phenomenon was either the work of visionary craftsmen, or the result of strong winds warping fresh wood (just like the tempest that distorted the unformed lives of Anna and Coop). Whatever the cause, it curls into the heavens like a strand of DNA. It is the perfect vantage point from which to view the book; it is also the controlling metaphor.

"We live permanently in the recurrence of our own stories," Anna notes, "whatever stories we tell." And they do not, exactly like the book, "move forward in linear development". Mimicking this process, the spire also circles upon itself. In other words, anyone who thinks there is such a thing as a non-porous divisadero is counting their chickens... So the book's title is a bluff; it really is a novel, not two novellas!

Staying in Dému, Anna has an affair with a Django Reinhardt type, and discovers that her subject's biography reflects that of her family. Her childhood trauma amid the broken glass of Coop's cabin is matched by that of young Lucien Segura, blinded in the left eye when a rabid dog crashes through his window. Perhaps that is why he is drawn to names that sound like spectacles or washing-powder; Lucette (his daughter), and Marie-Neige (the quasi-sibling for whom he has a taboo-lite desire).

Meanwhile, poker-faced Coop is learning his trade in Tahoe from a Dude-like character. Later he does postgraduate work with a less reputable mentor, and pulls off a noteworthy sting. But his triumph returns to bite him, when he is seduced into an adventure too far by his addiction to a six-foot blonde with a sea-green skirt. The blonde is familiar. She has to be Daryl Hannah, formerly a mermaid. And Coop? Who doesn't conjure up Gary Cooper when they hear that name?

This may be a problem. For all its highfalutin quotation, the book's DNA seems to be movie-based. Its plot developments (ice storm, card-table showdown, nocturnal couplings) feel as if hatched in a darkened movie theatre, rather than a fevered imagination. Even the name of the supposed French writer Lucien Segura has an equivalent in the IMDb (that of an obscure Continental director). Lucien is not the only one to suffer from monoculism, either temporarily or permanently; the same happens to Coop, and (obviously) One-Eyed Jacques.

And I fear the same may have happened to Ondaatje himself. At any rate, I spy the auteur glued to a movie camera, his cycloptic eye missing no detail as his characters run endlessly around the spiral tower at Barran. Divisadero may be a work of great ingenuity and beauty, but it is also a transparent thing, through which the light shines, but casts no shadows.

Clive Sinclair's 'Back in the Saddle Again' will be published next year by Picador

Bloomsbury £17.99 (273pp) £16.19 (free p&p) from 0870 079 8897