I can't remember who recommended this book to me. It must have been the author or a friend of his, because it's a fairly shallow dive into a seemingly random array of books, many of which I've never heard of, let alone read.
And the dive isn't particularly illuminating. I don't know what I was expecting when the way in was the choice of title and alternative never-weres, but it seems like the author wasn't either, as we get occasional recitations of the plot or true history behind a work, some ruminations on what was going on in the work's author's life, and some of the titles which lost out or a fairly obvious etymological dissection of the actual title.
It's written a little better than I'm making out, but it's scattergun and slapdash, and doesn't have much insight.
The most interesting thing by far is the testy exchange between Arthur Guittermann and Arthur Conan Doyle, in which Guittermann penned "The Case Of The Inferior Sleuth", a scorching critique in a fantastic sonnet accusing Doyle of denigrating Poe's seminal detective Dupin and of downplaying his influence on the character of Holmes. Doyle riposte was equally scorching, and also in sonnet form, explaining patiently that it is Holmes who denigrates Dupin, as a character flaw, and that it is obvious that Doyle venerates him and acknowledges the influence, you dickwad. He didn't use exactly that language, but it's pretty clear it was probably in the first draft.
There, I've told you the best bit: no need to read this one. A far book for this type of thing is Alastair Grey's The Book Of Prefaces, which were i reading it now would get all the stars avaialble.