This is a sort of literary biography of Bram Stoker, tracing a variety of influences that might have contributed to his creation of the Dracula character (and the novel Dracula in general). It's got a lot of Victorian theatrical history and interesting tidbits about Oscar Wilde and Walt Whitman as well as some figures you're far less likely to have heard of.
I think the strength of the book for me was that it was looking at a diversity of influences. As a writer, I feel like it's almost never the case that inspiration is linear and traceable, even for me, much less for people who don't know the random stories and associations I might have in detail. So while Steinmeyer is talking about how this or that might have influenced Stoker, he's very clear that having one true mapping is just not reasonable and just not going to work. He can give you various threads of influence without claiming that he knows the inner workings of the author's psyche--which is a very good thing indeed.
There were some small infelicities that I hope will be cleared up in the final version (I got an ARC), but the main thing that bothered me was the organization. It felt like Steinmeyer went back and forth a lot, focusing on neither a chronologically unified nor a personally unified narrative--bits of Wilde here, bits of Wilde there, and so on. But even with the back and forth, it was fairly easy to follow what was going on and why. If you're interested in Stoker's influences or even in the bits of Victorian theater that were vastly important at the time and almost completely forgotten now, this book will be useful.