The novel is essentially a dark mirror of the Sherlock Holmes mythos, with Holmes and Watson replaced as protagonists by a pairing of Professor Moriarty and Colonel Sebastian 'Basher' Moran (who is employed as a hit man for Moriarty's organisation). Newman isn't the first writer to tackle Moriarty (John Gardner's Moriarty novels, Michael Kurland's Professor Moriarty series and, especially, Neil Gaiman's Cthulhu mythos story A Study in Emerald spring to mind). However, this book brings to the mix Kim Newman's characteristic brand of highly literate intertextual pastiche populated with historical and fictional characters.
The novel consists of a cycle of seven linked stories - in part a paste-up of stories that have appeared elsewhere - told by Moran through the vehicle of their alleged discovery in a despatch box in a London "criminal bank". A Volume in Vermilion sets the scene - the first meeting of Moran and Moriarty is excerpted on the Titan books website here - then tells of Moran's first assignment involving the Mormon-linked feud from Conan Doyle's A Study in Scarlet. A Shambles in Belgravia is a pastiche of A Scandal in Bohemia involving Irene Adler (Moran writes: "To Professor Moriarty, she is always that bitch") and a blackmail plot involving the royal family of Ruritania (i.e. from Anthony Hope's The Prisoner of Zenda). The Red Planet League tells of Moriarty's convoluted plot, involving Martians, to discredit an egotistical Astronomer Royal who has dissed his Dynamics of an Asteroid monograph. The title story, The Hound of the D'Urbervilles, retells The Hound of the Baskervilles in Thomas Hardy's Wessex, in which Moriarty is hired by an emigree American robber baron to dispel myths of the giant hound that are interfering with his plans to squeeze profits from the D'Urberville estate. The Adventure of the Six Maledictions uses as starting point J Milton Hayes's music hall monologue The Green Eye of the Little Yellow God (concerning "Mad Carew", who steals a cursed gem) and follows the mayhew that arises when Moriarty, for reasons of his own, decides to start collecting cursed objects. The Greek Invertebrate is a steampunk thriller that takes Moriarty and Moran, along with a cast of characters from Arnold Ridley's The Ghost Train, to "Fal Vale" in Cornwall to investigate sightings of a sinister "white worm". The Problem of the Final Adventure goes to Europe and, inevitably, the Reichenbach Falls, interweaving the events of Conan Doyle's The Final Problem with Moriarty's final encounter with his own nemesis (perhaps surprisingly, not Sherlock Holmes).
For the most part, this is extremely well done. Colonel Moran, as a narrator, strongly resembles a nastier version of George MacDonald Fraser's Flashman - a debt acknowledged by Newman - and proves similarly sympathetic; he has a vestige of honour (he admires courage), is aware of his own failings, and is far too interested in people and their motives to be the complete cynic he professes to be. Likewise the relationship between Moran, the adrenalin junkie ex-soldier, and Moriarty, the unfathomable intellectual, is well-developed as a parallel to that of Watson and Holmes (where Holmes keeps bees, Moriarty keeps wasps; and his "methods" are contrary to Holmes' deduction; Moriarty does the Victorian equivalent of Googling it).
If I have a criticism, it's of Newman's handling of the intertextualism. He can do it seamlessly, subtly and pertinently; and he can go into an "everything but the kitchen sink" mode, throwing in large numbers of out-of-mythos characters and allusions that make you lose suspension of disbelief. The best story of the collection in my view is The Red Planet League, and that does it exactly right; it's a tightly-done skit on alien invasion literature and film - chiefly HG Wells's The Crystal Egg and The War of the Worlds ...
Yet across the gulf of the lecture hall, a mind that was to Stent's as his was to the beasts that perish, an intellect vast and cool and unsympathetic, regarded the podium with envious eyes, and slowly and surely drew his plans against him.
... but also with hat-tips to Invasion of the Body Snatchers, Heinlein's The Puppet Masters, and even briefly to Alien. But in the otherwise excellent The Hound of the D'Urbervilles, Newman starts bringing in out-of-mythos characters, such as Desperate Dan and a character who is clearly Klaus Kinski. And The Adventure of the Six Maledictions is in full-on kitchen sink mode, complete with the Hoxton Creeper (as played by Rondo Hatton in The Pearl of Death), the Maltese Falcon, and a whole cast of criminal masterminds from book and film, who appear again in The Problem of the Final Adventure. They're still good stories, but you can see the wheels working.
This really is a book where you need to read it once, read the footnotes and Google a bit, then read again, then Google again. There are any number of interesting-looking works referenced that I'd never heard of, such as William Hope Hodgson's Carnacki stories. And it's often very difficult - a sign of good pastiche - to distinguish fact from invention on first reading. For example, Newman's learned footnote about "quap", "a form of pitchblende used in turn-of-the-century patent medicines", looked thoroughly plausible until I found it come from HG Wells's now little-read semi-autobiographical satire Tono-Bungay. I enjoyed Moriarty - The Hound of the D'Urbervilles a lot, and will no doubt be pursuing the threads for a while to come.