The plot is simple: what if the outcome of World War I depended upon the contents of a telegram, and Britain were desperate to know the contents of that telegram? Well, it did. The story of the Zimmerman Telegram is historical fact. Meyer's inspired move is to couple that fact to Doyle's (or Watson's) story "His Last Bow," which hints at Holmes's role in the war about to engulf Europe. And thereby hangs a tale that takes Holmes and Watson in their twilight years from London to Washington to Mexico City, dogged by assassins every step of the way.
The truth is, this isn't really a detective story, though it's strewn with Holmes's customary legerdemain. And it's not really a spy story, though Watson can hardly turn around without bumping into a spy. It's a coming of age story for a man in his sixties who has come to realize that his fog-bound streets, hansom cabs, and skills at single-stick are not enough to see him through the dangerous new world of the 20th century. He must confront his own parochialism, the smallness of his lifelong efforts against evil.
Don't misunderstand me. There's plenty of adventure and derring-do in this novel, but there's an elegiac mood to it, too. And that raises it above Meyer's previous efforts. Which makes it all the more worth the read.
Sherlock Holmes and the Telegram from Hell
[I wouldn't add this in a review for Amazon or Goodreads since I don't think a review should be about the reviewer, but if you're reading it on my blog, you know that I've written some Sherlock Holmes novels myself, and have some idea of the pitfalls involved in this kind of novel. And you've probably heard me mention that Meyer's The Seven Per-cent Solution was the inspiration for my own efforts. So imagine my consternation when, in the middle of editing The Strange Case of the Pharaoh's Heart, I learned that Meyer was about to come out with his own Sherlock Holmes meets the mummy tale, The Return of the Pharaoh, and how relieved I was to learn that the pharaoh in his tale was not Tutankhamun and his story was nothing like mine. Which is preface to say that I came upon the story of the Zimmerman Telegram about a year ago and contemplated writing a Holmes short story based on it. I thank procrastination I didn't go ahead with that one.]