The shape of snakes Book

This is the 3rd of her books that I've read, and the one I've liked the least. The characters are all unpleasant, the story quite slow, and the constant hints that you can't quite trust the narrator are a bit annoying. Annie, an black woman with Tourette's syndrome who lives alone and is shunned by her racist neighbours, is found dying in the street where she lives in South London during the Winter of Discontent. M finds her and is sure she's been murdered, but no one believe her and the police investigation goes nowhere, leading to her nervous breakdown and the near end of her marriage, so she and her husband Sam move overseas and agree not to talk about it. Twenty years later, they move back to the UK with their sons and M continues her own investigation of what happened, going to alarming lengths to try and get justice for Annie, but everyone has secrets and their own agenda.
As a cat-lover I found the descriptions of animal cruelty absolutely sickening, and sort of wish I hadn't read this at all. The story is cleverly told in the first person POV but with copies of letters, emails and official reports adding to M's narrative, each one twisting the story a little more. It's well written and I will read more of her books, but suggest caution with this one.