How did a nice girl like JuJu end up in jail?

The Judds are your average, everyday, upper-middle-class British family. Charles and Daphne, the parents, have retired to Cornwall so he can golf while she obsesses over flower arrangements at the local church. Son Charlie is making a fortune selling socks over the Internet. Lovely, waif-like daughter Sophie has a job in advertising and a bachelorette pad in London.

Then there's the other daughter, Juliet - adoringly known as JuJu - busy serving two years in a federal prison near Buffalo, NY, after trying to fence a stolen Tiffany window.

Thus ends the Judds' attempt at normalcy, and thus begins The Promise of Happiness, the dry, witty, but achy novel by South African writer Justin Cartwright.

The Judds are not pretentious people. They never expected more than a modest share of happiness in life. Indeed, their collective life trajectories seem to trace paths of diminished expectations.

Charles and Daphne live together in "a fine mist of resentment which neither of them can quite dispel." Charlie, who is about to marry a beautiful woman he doesn't love, is vaguely ashamed of having made so much money selling a product he never sees, dependent on the skills of two computer-geek employees whom he vaguely regards as "exotic pets."

But with JuJu's disgrace - broadcast worldwide by the press - it seems that their sense of themselves as a reasonably successful family unit has been shredded.

JuJu was almost a religion for the Judds. Bright and beautiful, an Oxford grad and art history scholar, her infatuation with lovely objects was to them "evidence of the human striving for the impossible." (Younger sister Sophie insists, "She has the look of someone made in heaven.")

Charles, who doted on his older daughter, has been the most devastated, although the entire family seems to have been frozen in grief during her two-year imprisonment.

The novel opens on the day of her release. Charlie has flown to Buffalo to collect her. Most of the book is about the slow drift toward an eventual family reunion as brother and sister wend their way home.

As they wait, each family member tries to sort through the "penumbra of moral ambiguity" into which events have cast them.

Charles's search is the most painful and complicated. He's racked with guilt over the fact that he never visited JuJu in prison. At the same time, he's still reeling from wrongs done him by the prestigious accounting firm that once employed him, even as he finds himself increasingly a misfit in an England now populated by immigrants and people who chat on the Internet (a device which is no more than "a moronic inferno, with spelling mistakes," as far as Charles is concerned).

He views his wife as an irritating, alien presence. (He describes her as a solid woman, "filled with middle-aged substances of mysterious origin.") But neither does he receive much solace from an encounter with Jo, a former paramour, whom he finds "seems to have joined the army of anonymous disappointed women."

Daphne, meanwhile, refuses to let go of hope. Even as she haplessly mangles recipe after recipe in her Cornwall kitchen, she goes on fighting for her family, somehow imagining that if she can just turn Charlie's wedding into a perfect, flower-strewn pageant, the Judds will be able to heal.

The fierceness of Daphne's fixation is such that even Sophie (who has drifted into a cocaine-infused haze and an affair with a married man during her sister's absence) begins to buy into her mother's plan for salvation. "Look, the Judds are where they belong after a few glitches," Sophie begins to muse one day after a few drinks have prompted her to ponder the potential power of her brother's wedding. "Englishness has healed them! Jerusalem!"

Charles, however, has no such hopes. As her husband disintegrates, Daphne treats him with distracted patience, remembering that he once had thick, tousled, Ted Hughes hair, "pretty advanced for an accountant." Even Charles's dog appears to have committed suicide - although (along with the question of JuJu's guilt) appearances in this story often prove to be misleading.

There is an air of desperation that hangs over the novel, but Cartwright is always slyly sympathetic to his characters and it's almost impossible not to become engrossed by the Judds and to root for them to achieve some sort of redemption.

The fact that they might succeed is hinted at by the name of the window JuJu is accused of stealing: resurrection. But it's also evident in the love that somehow survives the disappointment.

The Judds may not be perfect but at least they never forget that they are a family and all accept the responsibility to do whatever is possible to keep the others afloat. Cartwright does hint that perhaps they believe in each other only because they have so little else to cling to, yet their solidarity is touching nonetheless.

In Britain (where Cartwright has racked up other honors as well) "The Promise of Happiness" received a 2005 Hawthornden Prize. Readers there seem particularly drawn to his skill at tempering flashes of feeling and insight with dampening sarcasm.

"JuJu and Charlie and Sophie have never been out of my thoughts," Charles tells himself as he lies in the hospital recuperating from pneumonia. "I have been selfish and foolish, but if anybody asked I could honestly say I have never passed a single day without thinking about them."

Cartwright quickly adds: "It's probably the effect of the drugs, but he feels warmly affectionate toward his absent children." That's about as cozy and cuddly as this story ever gets, but somehow, it's enough.

• Marjorie Kehe is the Monitor's book editor.