What lies behind the sealed door at one of Harrogate's most historic buildings is the question being asked by the town's most distinguished historian.
Malcolm Neesam is convinced there is the possibility that the basement of Grove House contains the long-lost 'secret laboratory' of Samson Fox, the legendary 19th century multi-millionaire inventor and philanthropist.
It's a subject he says is not only important to the town but is also dear to the heart of an acting dynasty related to one of the founding fathers of modern Harrogate.
Malcolm said: "The Fox family continue to be intensely interested in Grove House and its fate, especially Edward Fox OBE and his daughter Emilia Fox.
"Both of them visited Harrogate in 2012 when a plaque was unveiled commemorating Samson Fox and Grove House."
Located on Skipton Road, the stunning Grove House is a Grade II* listed and has been owned since 1926 by the the R.A.O.B. (Royal Antediluvian Order of Buffaloes), a philanthropic society with dozens and clubs, lodges and provinces across the region.
Fox lived at Grove House from 1882 until his death in 1903, turning it into a true home, albeit one lavishly set out, complete with Turkish Baths, stables and a fully-equipped, private, underground laboratory.
It's this part of the story Harrogate historian Malcolm Neesam, whose books include the Harrogate Great Chronicle 1332-1841, has been intrigued by for nearly 30 years.
Malcolm's interest was reawakened as he worked on his next major publication.
Malcolm said: "When, I was researching Samson Fox’s life in the 1980s, the then Grand Secretary of the R.A.O.B. told me that Samson Fox’s lost laboratory was believed to have been located on the eastern side of the building following the cracking of some concrete in the side garden.
"Because of lack of funding and insufficient interest, no further action was taken to investigate, or indeed to open up the sealed doors in the basement."
"I became interested in the subject again because I am telling Samson Fox’s life story in my next big Harrogate book."
The remarkable inventor Samson Fox, who went on to be the hugely influential mayor of Harrogate, lived at Grove House from 1882 until his death in 1903.
One of his most extraordinary inventions was for the domestic application of water-gas which he tested out at first at Grove House.
Thus it became the first house in Yorkshire to have lighting by water gas.
As Harrogate became the place to visit for the aristocracy and royalty, Fox also ensured Parliament Street was also lit by this means, becoming the first such thoroughfare in the world.
Malcolm Neesam believes it's vital the basement is reopened and examined at some point for the good of history - and the town.
He said: "We should investigate the lost laboratory and possibly to add to our knowledge of one of 19th Britain’s most brilliant inventive minds.
"A proper investigation needs to be done. If even a fragment of the laboratory survives underground, it would add greatly to the historic value of the site."