Some hundred years after the death of Sherlock Holmes, a manuscript has been discovered in the vaults of Cox and Co in Charing Cross.
It recounts the events of a 'missing' Sherlock Holmes case, a case written up by Dr Watson for the sake of completing the Holmes canon but considered by him to be too shocking to be published in his lifetime.
Only now can the full story be told...
Sherlock Holmes has been consulted by London art dealer Edmund Carstairs.
A notorious Boston gang has inadvertently destroyed four valuable paintings during the course of a train robbery.
Carstairs persuaded a wealthy American benefactor to fund a reward for the capture of the Flat Cap Gang, but during the manhunt, one of the leaders of the gang was killed.
Now Carstairs is being watched by a man in a flat cap and he fears that the gangster's twin has followed him to London to exact revenge.
The man who has been terrorising Edmund Carstairs has been found dead in a hotel room, but who, Sherlock Holmes wonders, killed him and why? And did the young boy Ross, who is one of the Baker Street Irregulars, and who was watching the hotel on the night of the murder, see more than he is letting on?
One of Sherlock Holmes' young informants has gone missing.
Concerned for his safety the detective has visited Chorley Grange School for Boys, the institution from which Ross ran away earlier in the year.
Though the headmaster has no idea where his young charge has run to, one of Ross's friends recalls that he had a sister who worked at a public house called The Bag of Nails.
Holmes and Watson are on the trail of the mysteriously named House of Silk.
Unable to find any information about what it is or where it can be found, Holmes reluctantly turns to the only person he knows who is possibly even better informed and better connected than he himself, his brother Mycroft.
Acting on a tip off, Sherlock Holmes has gone to an opium den in Limehouse.
Whilst Watson is waiting in a public house nearby, he hears a gunshot and rushes outside to find Sally Dixon lying dead in the street.
Lying unconscious beside her, with a gun in his hand, is none other than the famous detective Sherlock Holmes.
Sherlock Holmes has been arrested on suspicion of murdering the very girl who was most likely to be able to provide an answer to the conundrum of the House of Silk.
Whilst Watson sits at Baker Street wondering what to do, he is surprised to receive a visit from Catherine Carstairs, the wife of the art dealer who set this whole investigation in motion.
And he tries to find a link between the death of the girl in Limehouse, the death of the man in the flat cap in a Bermondsey Hotel and the destruction of four valuable paintings by a notorious Boston Gang.
Dr Watson has been abducted from the street and taken to an unknown address where a man who refused to identify himself warned him that Holmes' life is in grave danger; that the people who wish to keep the House of Silk a secret won't let his case come to court, and that the order has already been given that he must not leave prison alive.
Armed with the key to his friend's cell, Watson makes an appointment to visit the famous detective in the House of Correction.
The headmaster of Chorley Grange School for Boys has given Watson a flyer that was hidden in a book which belonged to the dead boy, Ross.
The advertisement is for Dr Silkins' House of Wonders.
Convinced he has finally found the House of Silk, Watson gives it to Holmes who has newly escaped from jail, and the two make their way to Jackdaw Lane.
Sherlock Holmes has exposed the dreadful secret of the House of Silk.
But still it isn't clear what links the house of ill repute to the destruction of the paintings by the Flat Cap Gang in Boston and the murder of the man in the flat cap at the hotel in Bermondsey.
And so he returns to where the case began, at the home of the art dealer, Edmund Carstairs, in Wimbledon.