Shortly after he has been dumped by his latest boyfriend, by text message, Barrett Meeks sees a vision in the sky over Central Park.

A shimmering light appears to him in the Manhattan twilight, which give him the feeling that God is looking directly at him. He tries to forget this unsettling event, but its influence continues to be felt throughout the four years over which this deeply moving, often amusing novel is set.

Barrett, once tipped to become an academic, works in a clothes shop and lives in a rundown apartment with his older brother Tyler and his very ill wife-to-be, Beth. Tyler, a singer-songwriter, snorts coke to help him summon the muse, and when we first meet him is wrestling with a song for Beth on their wedding day.

The bride, meanwhile, is by stages fading from life, emerging occasionally, like an earthly version of the fairy tale Snow Queen, dressed all in white. Hers is a tragic story, and yet Cunningham is not unaware of the friction a protracted dying can create. When one day Beth feels well enough to turn up for work at the shop, and instructs Barrett on how better to arrange their display of jeans, he reflects: "As it turns out, the mortally ill can be rendered more, rather than less, irritating by the authority impending demise confers upon them. Who knew?"

As with other of Cunningham's fiction, the three-character structure is central to the story, the brothers' close bond unusually tender because of their mother's freakish death by lightening years earlier, and the third party, Beth, aware that in marrying Tyler she is also taking on Barrett.

Though not all the story is set in winter, snow features large in the opening chapters. A hawk-eyed observer, whose emotional intensity is matched by a felicitous light-hearted descriptiveness, Cunningham lingers on the ethereal whiteness that transforms the brothers' dingy district: "Here's a fall of new snow, serious snow, immaculate, with its hint of benediction, as if some company that delivers hush and accord to the better neighbourhoods had gotten the wrong address."

Though told through the perspectives of his main characters, Beth's voice is a whisper, and the reader is in no doubt that the novel is Barrett's. The author of The Hours, his homage to Virginia Woolf, is unabashed in his torrent of interior thought, the flow of people's minds reproduced with conversational and parenthetical panache. Once one is accustomed to the plethora of asides, the story races on at full-tide. It is almost too fast for those who would like to relish the author's subtlety, and his artfully disguised technique, the tight construction of the novel nicely disguised as an easygoing unfolding.

Opening against the backdrop of the impending 2004 election that will see Dubya Bush re-elected, it closes shortly before the 2008 election that sweeps Obama to power. Tyler thinks constantly of the oppressed and the downtrodden, and is gloomily certain the Cain-Palin double-act will triumph; Barrett wonders if he will ever find love; and both, in the space of this novel, find answers of a kind to their artistic, emotional and intellectual strivings.

It is, for instance, a revelation to Barrett to realise that he is not a failure for not being a high-flyer. "God (whoever She is) does not need you, does not need anyone, to arrive, at the end, in the cloud field, with its remote golden spires, bearing an armload of earthly accomplishments." Tyler, meanwhile, strives to understand the nature of art, the propulsion to create, and to reconcile his need to write songs with his inability to write songs he thinks are good enough. To temper his perpetual disappointment, he switches from coke to heroin.

A work full of ideas and questions, it straddles spiritual, artistic, romantic and domestic life. The ebb and flow of his characters' lives, that of their friends and colleagues, and even of strangers they pass in the street, is instantly engaging.

There is a much humour too, as when he describes the handsome boyfriend of one of their brothers' friends: "Andrew, the descendant of generations of men who rode bold-hearted off into unknown territory, into the mountains and forests, while the others - the cautious, the unsure, those who were grateful for the little they had already - conducted their various businesses on the sooty cobblestones of the East, careful about puddles and piles of manure."

The Snow Queen is a delightfully entertaining, heart-searching work about the quest for meaning and the importance of the ordinary. It is an elegy to the commonplace and a paean to the universal desire to reach higher than that. Underlying it all is the knowledge that life is precious, fragile and fleeting.