'When all is said and done, killing my mother came easily,' is the bold opening line of Alice Sebold's new novel, The Almost Moon. With this chilling confession, any doubt about the author's ability to create a narrative as compelling as that of The Lovely Bones - in which a murdered daughter observes her family's continuing life from heaven - is quickly allayed.

Narrator Helen Knightly, at 49, is a professional figure model who has spent the two decades since her father's death acting as her mother's keeper. Dementia has taken over Clair Knightly, a long-faded beauty and agoraphobe, and one day, after another one of her mother's 'accidents', Helen suffocates her with a hand towel.

It was only putting her out of her misery, Helen thinks. And then she panics - it was also murder.

The Almost Moon follows Helen in the 24 hours after she kills the woman with whom she had a love-hate relationship, and whose life was coloured by mental illness. Helen beds her best friend's son in the cloudy hours after the death, and her ex-husband Jake, father of her two daughters and to whom she hasn't spoken in three years, is the only person she can think to turn to for help. Her efforts to avoid a police investigation play out in the initial stages of the book.

Sebold paces the novel to fit the mindset of a woman manoeuvring through extreme shock, despite her being the cause of it. As the plot develops the back story emerges: Helen's mother was not the only one who suffered from mental illness; her father did too.

Despite her flaws (matricidal leanings included), Helen is a sympathetic character.

Key details are doled out slowly; after her mother is killed Helen recalls that her father fell down the stairs. But each time she comes back to the story she admits a little more. Helen becomes increasingly open while approaching the inevitable (as she sees it: taking her own life before the police come, or facing life in jail), as she re-emerges from the initial distress of murder.

Realising that all these literary devices (save, perhaps, for the strangely soft ending) are all part of Sebold's grander intentions help make for a better read.