Last views of fragile happiness

As opening sentences go, "It happens that I am going through a period of great unhappiness and loss just now", doesn't exactly excite. But Carol Shields's latest book was never going to be a cause for celebration, because it's to be her last. Shields was diagnosed with terminal cancer three years ago and wrote Unless in what she describes as a "sudden surge of clarity". It feels like a last things novel, an attempt to communicate a newly acquired understanding of the fragility of happiness. It's a real shame that it doesn't quite succeed.

The narrator, 44-year-old Canadian writer Reta Winters, has her peaceful home and hearth existence shattered when her eldest daughter quits college and starts sitting on a Toronto street corner with a placard bearing the word "Goodness" slung round her neck. Why this happens is not important.

In fact, in a book almost totally devoid of plot and with no properly defined character other than the narrator, all that is important is the way that Reta thinks and, more particularly, writes.

She responds to the world around her chiefly in literary terms: "When did this part of the narrative happen? We know it didn't rise out of the ordinary plot lines of a life story." We're treated to endless updates on her own works in progress - translations of various French feminist tracts and a frothy comic novel called My Thyme is Up about a fashion journalist.

"I am too aware of being in incestuous waters, a woman writer who is writing about a woman writer who is writing," she says at one point. Quite.

This preoccupation with all things meta-fictional seems both baffling and clunky, flaunting its self-regarding irony rather too hard. Every chapter is titled with an adverb or a preposition - "Wherein", "Thereof ", "So" - which are supposed to be hints at morality, but actually just seem slightly vapid.

When Shields does have something to say, she spells it out: "I dust and polish this house of mine so that I'll be able to seal it from damage. If I commit myself to its meticulous care, I will claim back my daughter Norah, gone to goodness." So what wants to be an elliptic Virginia Woolfesque novella ends up as a York Notes on itself. The book's title is helpfully explained: "Novels help us turn down the volume of our own interior 'discourse', but unless they can provide an alternative hopeful course, they're just so much narrative crumble. Unless, unless." This eager over-statement is what principally separates Unless from Shields's acclaimed back catalogue. The inventiveness and humanity displayed in the Pulitzer prize-winning The Stone Diaries and the sly, compulsive Larry's Party seem in short supply here. Shields's highly-strung tone and defensiveness are perplexing - she seems to be pre-empting criticism of her book's slightness (just over 200 pages) by having Reta write "the reviewers seemed taken aback that my slim novel possessed any weight at all".

Unless is a frustrating read, and Shields's higher ambitions for it seem maddeningly out of reach. She can still reconstruct the humdrum nature of the mind's workings and of smalltown suburban life without equal - both have rarely felt so cloying. But her much-admired light comic touch and gift for understatement are absent. At one point, Reta explains that the reason she reads novels is to escape her "own unrelenting monologue". So why does Shields think that we're all so keen to get inside Reta's? Knowing the circumstances in which Unless was written helps to answer this a little, but doesn't help to make it any more readable.