The Vault by Ruth Rendell.*
After all his years on the job, Reg Wexford has finally retired. He and Dora have turned the carriage house of actress-daughter Sheila's Hampstead home into a second home, keeping their house in Kingsmarkham. Wexford is enjoying retirement, especially walking around and exploring London, but he admits to himself that he misses police work.
Enter Tom Ede, whom Reg had met years earlier when Ede was new to the Force. Now a Detective Superintendent in London, Ede asks Wexford to "consult" on a puzzling case.
During an inspection prior to some home renovations, a couple living in an affluent part of the city found four bodies dumped in what used to be a coal storage hole.
The staircase leading to the house from the hole was bricked over, and the outside entrance, a manhole cover, was also sealed. There's no identification on any of the bodies, though one of the two males has some fine jewellery in his pocket.
As expected, Wexford becomes almost obsessed with the case, and keeps on digging after the police have essentially given up.
As always, there is a second plotline involving Wexford's family. This time, daughter Sylvia has some complications with a romantic relationship.
The Vault is the twenty-third book in the Chief Inspector Wexford series. The first book in the series, From Doon with Death, was published in 1964. That (if my English-major math is correct) is 47 years ago. As a result, many readers worldwide have have plenty of time to become familiar and comfortable with Reg Wexford, his family and colleagues.
However, familiarity does not breed discontent here. Rendell's writing continues to be exceptional, and more Wexford novels are eagerly awaited by this reviewer!
*Many thanks to the publisher for the e-galley!