You Don't Have to be Good, By Sabrina Broadbent Chatto & WIndus, £12.99

Life after the Bea runs out

Missing people usually fall in four categories: young people in care, men in their twenties, middle-aged men and the elderly. Fortysomething women rarely vanish – though as one of the characters in Sabrina Broadbent's new novel notes, that's only because they disappear by degrees.

Bea Kemp is pushing 50. She's childless, has a paper-pushing job with Cambridgeshire council and is married to Frank, an aspiring writer who spends his afternoons photographing the Polish cleaning lady's "astounding" bottom. Other regular visitors include nerdy Adrian and teenage Laura, Bea's nephew and niece. Despite her share of regrets, hippy-dippy Bea appears a cheerful sort, so it comes as a shock when she fails to turn up at work.

As in her previous novel Descent – a roman-à-clef that tracked the demise of the author's own marriage – Broadbent again captures the realities of imperfect relationships. When the police investigate Bea's disappearance, Frank's lack of knowledge of his wife is exposed. Unable to lay his hands on any recent snapshots, he finds it hard to recall her job title or the colour of her eyes.

The person most affected by Bea's departure is sister Katharine, a busy medic who until now has viewed her sibling as a babysitting opportunity. Her well-managed life starts to unravel as she confronts some unpleasant home truths.

The novel turns out to be less about Bea's identity crisis than the impact that her disappearance has on those left behind. Children have always been a palpable physical presence in Broadbent's fiction. Here Bea's nephew, Adrian, with his brainy jokes and gawky hugs, is the novel's star turn. The flame-haired 13-year-old crawls into his missing aunt's wardrobe to inhale her "trail of molecular particles".

Broadbent's writing is funny and spry, and her characters nicely unconventional. Bea, however, remains a mystery. The mid-life fantasy of slipping away is a seductive one, and it's hard not to feel a little cheated when we're not allowed to accompany Bea over Midsummer Common.