Before I begin with this review, let's spare a moment to talk about the study questions that come at the end of this book -- it always leaves me a little bemused when authors and publishers elect to leave study questions at the ends of their novels, as if it's simply a matter of course that they will become set texts, but these were particularly interesting, because the first question asks if readers thought the plot twist at the end was fair and well foreshadowed, and the second question immediately opens by telling them that yes, it was, how dare they think otherwise.
A++ work there, whoever wrote those study questions. Given how the seeming insecurity about the plot twists matches up pretty well to how insecure the writer seems about it even in his own narration, I'm presuming it was Horowitz himself.
Set in the universe of Sherlock Holmes (Anthony Horowitz has rather made a living for himself writing what amounts to high class fanfic, these days, but never mind), Moriarty follows a Pinkerton agent, Frederick Chase, as he arrives in Europe to investigate an American mobster, Clarence Devereux, who has taken over Moriarty's business. Teaming up with Scotland Yard detective Athelney Jones, Chase sets about dismantling Devereux's criminal empire. But a mysterious third party continues to interfere with their investigation, and both Jones and Chase soon come to suspect that there is some deeper conspiracy at work.
If you read that synopsis and immediately went 'well, obviously either Chase or Jones is Moriarty,' then congratulations! You're everybody.
That's a problem, because in a lot of ways, the plot twist is the only thing this novel has going for it. The writing style is almost impossibly bland, and Chase makes for an incredibly boring narrator, to the point where I found myself not even caring about anything that happened. It was a story almost completely without pizazz, flair, or anything to maintain a reader's interest, bar a few scenes near the very end.
The writing style is very overtly trying to mimic Arthur Conan Doyle's, without truly understanding any of what makes Doyle's writing interesting to read. Horowitz instead seems to be much more in his element when writing his relatively faster-paced and (perhaps) slightly shallower Alex Rider or James Bond stories.
It doesn't help at all that our two leads are not tremendously interesting. Frederick Chase could best be described as a workaday everyman, blandly expressing surprise at everything around him but never really displaying any kind of personality of his own; and Jones' personality begins and ends at 'Sherlock Holmes fanboy,' and while the idea of somebody who desperately idolises Holmes but just isn't up to the task of imitating him is an interesting one, it never really pans out into any interesting directions, because by the end of the book, Jones has neither learned anything nor changed at all.
There aren't really any other characters, either. Devereux himself barely appears and has very little presence in the story at all, since he almost never makes any moves against Chase and Jones; one of his henchmen, Mortlake, has more of a story presence, but still not really enough of one to stand out; and there are basically no other characters on Chase and Jone's side bar Jone's wife, Elspeth, who has maybe two scenes in the entire book.
When the plot twist does roll around, we get nearly a full chapter of Horowitz (oh, I'm sorry, Chase) explaining how it was actually brilliantly foreshadowed, and literally walking the reader through all the moments of foreshadowing in the story so far. This is bad writing. This is also unnecessary writing, because the plot twist was obvious from the end of the very first chapter. If you are derailing your entire story to tell us all how clever you are, and to attempt to shut down claims that your plot twist was poorly written (and then doing so again in your study questions), then chances are your plot twist was poorly written.
Oddly enough, the book gets a lot more interesting after that twist -- post-twist Chase is miles more interesting and engaging to read than pre-twist Chase. Unfortunately, the book then ends one chapter later, and while there's an epilogue, it involves neither Chase nor any of the other members of the central cast.
All in all, I have to say, I found this book kind of disappointing. Both it and Horowitz's other Sherlock Holmes book, The House of Silk, have received rave reviews, but in all honesty I have no idea why. This just came across to me as a terribly dull, turgid book, one which had the seeds of something great but was shot in the foot by both its bland writing style and by its author's insecurities over his own writing.