This is Ruth Rendell during her top writing years, published 1984 the plotting operates on several cleverly interlinked levels. The characters are superbly drawn and absolutely believable.
Readers of RR seem to fall into two camps, there are those like me, older readers, who have followed her for many a long year and then there are newer readers, some may have found her through TV dramatisations. Those who have followed loyally for an age, are the ones most likely to be bitterly disappointed with her latest output and that is why I sometimes go back to these earlier books. They are all more than worthy of a second read because they are so heavily detailed.
Mindful of a spoiler from another reader, there is not a lot I can reveal about the plot. It centres around a young mother and her toddler, together her with her rather unhinged mum, who, in an attempt to be kind and helpful to her daughter, unleashes a devastating chain of events, which for me, end very satisfactorily. Some of the passages I found as a mum very upsetting but they had to be that way for the story to work. Well worth a re-read or, if you have only read later Rendell's do give this one a go