I am a sucker for Sherlock Holmes stories. I am incredibly happy to try anybody's fiction set in 221B Baker Street and give it a few hours. Anthony Horowitz, best known as a writer of British TV drama - notably the series Foyle's War and Midsomer Murders - obtained Arthur Conan Doyle's estate's authorization and approval to write this novel. He didn't need it, of course, as the character is in the public domain, but it lends the story a whisper of authenticity.
Holmes fanfic typically begins with a cute series of explanations as to why this story has had to be suppressed until now. This time out, Watson did not even write the events down until quite late in his life, after Holmes had passed away, and provided explicit instructions that they were not to be published for decades. Of course. That's all part of The Game.
Anyway, Watson recounts an occasion where Holmes' use of his Baker Street Irregulars gets one of the kids killed. It's a much more convoluted and involved story than any that Doyle had ever penned, taking in ruined paintings in America, criminal gangs, mysterious and malicious strangers, and an orphanage for wayward boys before reaching one of the lowest points of Holmes' career: his arrest for murder under the influence of narcotics.
One little quirk that I have about reading detective fiction is that I do not try to speculate ahead, and yet sometimes there's no getting around it. I don't want to figure things out before the protagonists do, but I suspect that the great secret at the heart of The House of Silk will be readily apparent to jaded 21st-century eyes, even if the prim and correct Dr. Watson would never imagine such horrors. As such, I found myself impatient with the narrative, urging it to move on. Horowitz does a good job capturing Holmes, Watson, Lestrade, and Mycroft, and his construction is solid, but it would take a Victorian to be very surprised by what's going on in this book. Recommended with reservations.