Referring back to an earlier post of mine (which in turn was prompted by various prior posts within this thread) and the topic of non-canonical works, I have now finished Mr. Hanna's novel and stand prepared to put forth my two-farthings' worth...
There may well be a subcategory within the milieu of Holmesian pastiche wherein the greatest of fictional detectives matches wits against the perpetrator of the most notorious of unsolved crimes: Holmes vs. Jack the Ripper. I am personally aware of two films and three novels, and I am reasonably confident that this figure only scratches the surface. Mr. Hanna's work falls within this subcategory.
Edward B. Hanna's The Whitechapel Horrors uses the "Royal Conspiracy" theory, and, while he does not follow the same path as Stephen Knight (Jack the Ripper: The Final Solution) many characters from Mr. Knight's book make appearances here (minus Robert Lees). Hanna's tale discards the Masonic underpinnings of Knight's "findings" and provides a different perpetrator from within the same cast. In fact, Mr. Hanna goes quite out of his way in some places to discredit Knight's claims, while at the same time paying an homage to them. (Not surprisingly, he lists Jack the Ripper: The Final Solution among the works he researched for this novel.)
The strength of any Holmes pastiche lies in two critical areas: how well the author "gets" Holmes, and how well whatever new element is introduced and interwoven into established canon. Obviously Mr. Hanna did quite a bit of research into Saucy Jack, and indeed between 98%-99% of the known facts (excluding, of course, contemporary--and later--speculation and the clues introduced for Holmes to discover) are as accurate as their myriad and often conflicting coverage can be. To his credit, however, he also did extensive research into Holmesian lore, and that shines as well. We get the "accepted" facts and chronology of the Ripper case overlain with the accepted "facts and chronology" of the lives and cases of Holmes and Watson (Mr. Hanna cites Baring-Gould, et al), so that we have canonical cases taking the Baker Street duo away from active Ripper investigation at all the logical and appropriate times, as well as an alternate theory for the Great Hiatus. We are rewarded by his efforts at real and fictional fidelity with a (pun intended) ripping good yarn worthy of Dr. Doyle himself.
As we are (or at least most of us are) relatively familiar with the Ripper investigations, there is no need to provide a plot synopsis; merely add Sherlock Holmes to the mix. (If you are one of the few not familiar with the particulars of this case, there are plenty of places to look online, as well as within Mr. Hanna's bibliography to The Whitechapel Horrors. For my money, the best of the lot is Donald Rumbelow's The Complete Jack the Ripper.) The points worth discussing (that don't involve spoilers) then are Mr. Hanna's foray into the Doyleverse. The tack of most writers of Holmesian pastiche is to emulate Dr. Doyle himself, and write from the first person notes of Dr. John H. Watson. Some do this well, others do not. Mr. Hanna sidesteps this entirely by presenting this tale in the third-person, as a modern editor working from Watson's incomplete notes on the case. Thus, the point of view of the story switches from Watson to Holmes to back again. He does this so well, however, that I wonder why he didn't simply attempt the Watson-Voice throughout, as I found myself, indoctrinated as I am, subconsciously changing pronouns to make it just so. It is to Mr. Hanna's credit, therefore, that he clearly "gets" how Dr. Doyle wrote Holmes and is true to that spirit. Further, at no point does Mr. Hanna have any of his fictional characters doing anything inherently out of character with how they are established in canon.
For example, he doesn't throw in any situations or circumstances of the sort which catapult readers out of the realm of believability (neither of the historical case and record nor the Holmes canon) in lesser done pastiches. Holmes is inserted seamlessly into the reality of the case; makes realistic (and realistically Holmesian) deductions and discoveries; takes realistic (and realistically Holmesian) action; and comes to realistic (and realistically Holmesian) conclusions. At no point during the tale are we jolted out of the author's established reality, and even within Holmes' conclusion adherence to the historical record is maintained. Commenting further than this takes us inexorably into spoiler territory, which would be a disservice to those of you yet to read this novel.
In addition to citing both his Holmesian and Ripper resources, Mr. Hanna has provided end-notes worthy of a scholar. He makes comments on both the fictional and historical personages and events, provides context, and even calls Dr. Watson to task on his faulty recordings of the dates (in the last instance, cleverly, may I add). This perhaps more than anything else (in addition to Mr. Hanna's fidelity to both fictional and historical source materials) makes this pastiche stand out from so many of the lesser works.
While we are within this subcategory of the genre, allow me to briefly mention the other two Holmes/Ripper tales with which I am familiar. One that may or may not be worth your time (depending on your particular preferences), is Michael Dibdin's The Last Sherlock Holmes Story. As with The Whitechapel Horrors, a plot synopsis becomes irrelevant unless one is divulging spoilerish data. Mr. Dibdin uses the Watson-Voice to within an inch of its life, at points seemingly trying to out-Doyle Dr. Doyle himself. I will grant that it has been some long years since I've read the complete canon, but I don't remember it being quite so stilted throughout. As with Mr. Hanna, Mr. Dibdin fully integrates Holmes into the Ripper case, making neither seem like a "tack-on" to the other, but he goes on a completely different track. While logical (although stretching credulity at certain points, in my opinion), and it all makes sense in the end, the denouement (which is telegraphed) will leave some readers with an odd taste in their mouths.
Much, much better is Lindsay Faye's Dust and Shadow. It is superb. Even more than Mr. Hanna, Ms. Faye truly gets Holmes. Furthermore, she has the greatest sense of the Watson-Voice of anyone since Dr. Doyle himself. She does steer away from Stephen Knight territory, and offers up a completely new (and imminently logical and believable) perpetrator (fictional, of course), although I figured out who the killer was (but only by a few pages) before our heroes (through no fault of the incomparable Baker Street team; I, as well as many other "modern" readers, have a greater understanding of criminal psycho-pathology than was even available to Holmes in 1888). I can only say that if you haven't read Ms. Faye's novel, it should definitely be placed on your list.
(And here's a completely unrelated parenthetical sentence, just because I don't think I put enough in that one sentence...And yes, I am self-snarking.)
That, then, are the three Holmes/Ripper pastiche novels of which I am aware. If there are more, I would be most appreciative if someone would point them out to me.
As to the two films, I've only seen one of them, and I highly recommend it. Bob Clark's Murder by Decree is absolutely and firmly within the Stephen Knight camp (although the names of Gull and Netley have been changed). Although discredited, Knight's version of the Ripper case provides what most others don't--drama, intrigue, romance--which clearly accounts for its popularity with fiction writers (Alan Moore's From Hell also springs from Mr. Knight, to give only one example). The "Royal Conspiracy" theory has it's greatest telling in this film, with Holmes following the clues and bringing an end to the killings. Starring Christopher Plummer and James Mason as Holmes and Watson, respectively, this is a Holmes pastiche that I would say is a must-see, fans of Saucy Jack tales or not. The final scenes, with Mr. Plummer confronting and dictating terms to the circle of conspirators, is heart-rending. This is one of the few films where we see Holmes display some of the compassion and righteous indignation he is credited with by Dr. Doyle, and Mr. Plummer pulls it off without making us think he is doing anything inherently un-Holmesian.
(For the completist, the other film is James Hill's A Study in Terror, but as I've never seen it, I am unable to comment upon it.)
That, then, is my report to date on Holmes pastiches worthy of your time: two novels, one film (in addition to the ones mentioned in my previous post). As always, I appreciate the opinions of others, and further request that my attention be brought to works unknown to me which you recommend.