In The Vault, Ruth Rendell has done something very unusual. She has written a sequel to a stand alone novel (published twelve years earlier) and the sequel is a part of an on-going series. The Vault is the 23rd novel in the Inspector Wexford series. The crime that is investigated in this book is related to the events in that earlier book, A Sight for Sore Eyes, which did not feature Wexford, or for that matter any police detectives.
This is also a story about Wexford after retirement. Wexford has become quite a walker while living in London, and the walks he takes during the investigation are described in great detail. We are privy to his inner dialogues about the beauty of the city, the joys of walking, the joys and challenges of retirement. In the earlier Wexford book I read, The Monster in the Box, there is an emphasis on how books have always been important in Wexford's life. The love of books continues in this book.
I have noted in recent reviews that the Wexford books have a slow pace. A lot of the story is about Wexford's personal life. This may not be to everyone's taste.
Rendell is a very skilled writer, no matter what kind of story she is telling. She delves into relationships between co-workers, family members, neighbors. She develops major and minor characters in great detail. She conveys all of this as the story develops.
I am deliberately avoiding detail about the actual crime being investigated in this novel, in case readers want to start with the earlier book, A Sight for Sore Eyes, published in 1998, which did not feature Wexford. I found it to be a satisfying story, but I don't know how much that was colored by having just read the novel that sets up the situation. I can see benefits to reading it both ways, without the background and with.
Links to my reviews of books by Ruth Rendell:
The Monster in the Box (2009)
A Sight for Sore Eyes (1998)