Georgie has been left by Rip, her posh husband; they share custody of awkward, apocalypse-obsessed teenager Ben. Lonely and miserable, she gets pulled into the orbit of the ancient Mrs Shapiro, the least hygienic character in fiction since Fungus the Bogeyman. Lewycka glories in descriptions of her hopelessly filthy house and unutterably repulsive meals and cats, which turn the centrepiece of the novel - a potentially valuable property - into a house of horrors.

After being named as Mrs Shapiro's next-of-kin when the old lady has an accident, Georgie finds herself the focus of attention from two evil estate agents called Diablo and Wolfe, as well as from Ali the angelic handyman, his family, and large numbers of people from the social services - all intent, it seems, on prising this tatty but prime slice of real estate out of an old woman's hands.

Much of the humour is pun-based, and a little stretched. But Georgie is a lively, intensely sympathetic narrator, even if her innocent lack of knowledge about social services and, frankly, any Middle Eastern history is a little hard to swallow in a character who's meant to be a fortysomething writer. Yet the mystery at the heart of the novel - who is Mrs Shapiro, and what will happen to the house? - rather peters out; the arch-baddie, Wolfe, simply disappears.

In truth, the focus seems slightly off: the heart of the book should be working-class Georgie's marriage to the upper-class, arrogant Rip. Every time the spotlight falls there the book becomes riveting - how they fell in love, how she handled his family and he hers, the effect of their split on the children.

Yet we never see Rip's reasons or point of view. Instead, every time the book touches on real lives and what it's actually like these days holding a marriage together as the children grow up, we are hauled back far too quickly to the big, dank house overrun with cats, where comedy Middle Easterners and various mittel-Europeans mangle English in endearing ways.

Likewise, the novel's other great strength - the flashbacks to Mrs Shapiro's early life and her great love, Artem - are swiftly abandoned and even become a little foggy at the end. Instead, much time is spent going round B&Q or glue exhibitions (Georgie writes for a glue trade magazine, and thus discusses every set of human relationships in terms of adhesive bonds, rough-surface epoxy, etc, which is either charming or wearing, depending on your tolerance for glue trivia).

There's also a romantic novel, started but not finished by the heroine, that may remind readers with long memories of Sue Limb's wonderful Dulcie Domum. A dashing hero, a passing fear of the world ending, a confused boss, really a lot of glue, and many scenes set in Sainsburys - Georgie's book has as many different strands as Mrs Shapiro's house has rotting carpets. It's just too much. Less clutter, and the opportunity for the two natural and marvellous stories of Georgie and her family, Mrs Shapiro and hers, to intertwine more simply, would have clarified the voice and given more heft to a novel that is brimming with warmth and busyness but, like Mrs Shapiro's house, could really have done with stronger foundations.