The Vault (Inspector Wexford, #23)

The impossible has happened. Chief Inspector Reg Wexford has retired from the crime force. He and his wife, Dora, now divide their time between Kingsmarkham and a coachhouse in Hampstead, belonging to their actress daughter, Sheila.
Wexford takes great pleasure in his books, but, for all the benefits of a more relaxed lifestyle, he misses being the hand of the law.
But a chance meeting in a London street, with someone he had known briefly as a very young police constable, changes everything. Tom Ede is now a Detective Superintendent, and is very keen to recruit Wexford as an adviser on a mysterious murder case.
The bodies of two women and a man have been discovered in the old coal hole of an attractive house in St John's Wood. None of the corpses carry identification. But the man's jacket pockets contain a string of pearls, a diamond and a sapphire necklace as well as other jewellery valued in the region of £40,000.
To Wexford, this is definitely a case worth coming out of retirement for. He is intrigued and excited by the challenge, but unaware that this new investigative role will bring him into extreme physical danger...