Barbara Vine is one of my favorite writers. I have about three modern writers that I'll read anything they write, Barbara Vine (who also writes as Ruth Rendell), is one of them, the other two being P.D. James and Minette Walters.
This book was not one of my favorites though. I enjoyed it well enough, but I didn't love it.
The story is told by someone who is reflecting back on an event in her life. She's telling a story about a situation that she observed, something that was happening around her, but something that did not directly involve her. She was hired as a nurse for a family to care for their adult son. During her stay, she learns many disturbing family secrets and witnesses many strange events, leading ultimately to a tragedy.
But the story doesn't leave much of a impact. I felt no urgency to finish the book. It didn't arouse any intense feelings, no anger or suspense or fear. It does paint an interesting portrait of rural English life, as do many of her books. I felt like there was too much distance between the narration and the action of the story. Readers were never allowed inside the heads of the people actually involved, so you're left to assumption and speculation along with the narrator.
If you're looking for a good suspense, thriller though, there are several others that I would recommend over this. Two of my favorite Barbara Vine books are No Night is Too Long and Dark-Adapted Eye. I highly recommend both of those. This one, though, not so much.