This book has nothing to do with Chinese astrology – though the protagonist, Pearl, wishes she had some guide to what is written in the stars. Her life has been turned upside down by the sudden death of her mother in late pregnancy. The result – or the cause, in Pearl's mind – is her premature half-sister Rose, who looks nothing like the bonny baby she had imagined. Rose is the Rat.

This was one of the two "books of the fair" at the Bologna book fair last year (the other being Sally Green's Half Bad), and, although a rush of interest and deals is not a firm guarantee of quality, this debut certainly introduces a strong new voice in Young Adult fiction.

Some people will hate it because, with its tragic central premise it could be categorised as "sick-lit" – a relatively new genre that began with Jenny Downham's Before I Die and Sally Nicholls's Ways to Live Forever, and culminated in John Green's teenage death-fest The Fault in our Stars. The subject is a difficult one to negotiate, particularly when there is a young first-person narrator.

Reading it as an adult, one might feel the urge to shake Pearl, who is so immersed in her own grief that she won't lift a finger to help her previously adored stepdad, and hates everyone and everything. But a teenage reader won't react in that way. Pearl's is the voice of any self-absorbed 16-year-old, with the trauma of loss added on.

So far, the synopsis sounds like the many other "real-life" dramas that are supposed to be winning back YA fiction from the paranormal and fantasy. But there is a supernatural element in this book: Pearl's mum is dead but she won't lie down. As early as her own funeral, Stella is back, materialising in the church after the mourners have gone.

And she is no more the idealised perfect mother than the Rat is a model baby. Stella is a straight talker, who tries to pull Pearl out of her wallowing grief. She is a smoker too – "one of the few advantages of being dead is that you can finally stop giving things up".

The trouble is that Pearl can't be equally honest with her mum: she can't tell her that she hates the Rat and dreads her coming out of hospital and back home. And she can't summon Stella; sometimes she longs for her dead mother to be there and begs her to show up, but Stella is as unreliable as we come to suspect she was in life.

There is something else that can't really be said: that it was Stella's own carelessness that caused her death. She had missed a midwife appointment and had a terrible headache – a symptom of the eclampsia that would kill her.

Stella tells Pearl that having a second baby after such a long gap was her stepdad's idea, that his mother is an ogre who never liked her. Gradually we – and Pearl – see the half-truths and the omissions, as the remainder of the family struggle through the first year of bereavement.

There are painful reminders of how impossible it is to say the "right thing" to someone suffering the trauma of loss, as Pearl's former best friend Molly discovers. And then there is the nascent love story, which seems obligatory in any YA novel, as Pearl begins to fall for a neighbour's grandson. "The world may tip at any moment" is a hard lesson that Pearl learns, but tipping is not the same as ending, and she learns that too.

• Mary Hoffman is the editor of Daughters of Time (Templar). To order The Year of the Rat for £10.39 with free UK p&p call Guardian book service on 0330 333 6846 or go to guardianbookshop.co.uk.