It's been a while since I've delved into a Holmes pastiche, so it's difficult to say whether this particular offering brings anything new to the genre. [I know a number of other writers have tackled a view of Holmes from a female point of view and have written Holmes as the romantic interest in a relationship with a woman who is his intellectual equal. In this instance, the protagonist has feelings for Holmes that are not reciprocated. She is not, in fact, the woman who cracks Holmes' icy exterior, at least not in a way that has them ending up in bed together, so that's something.
The Devil's Grin is the story of Dr. Anton Kronberg, who really is Anna Kronberg, a woman masquerading as a man in Victorian London so that she can practice medicine. It wasn't common, but certainly not unheard of, for a woman to become a physician in England circa 1890, but Kronberg is German and the story explains that it was illegal in German for a woman to become a doctor and that Kronberg had to keep up the ruse once she left Germany for Boston and later London because once started it couldn't be stopped or she'd lose everything. As Anton Kronberg, she becomes a renowned expert in the budding sciences of epidemiology and bacteriology. She meets Holmes when the Metropolitan Police consult her about a person who may have died of cholera washes up in the Thames. There's no apparent crime, but both Kronberg and the Great Detective are intrigued by the mysterious death and end up on the case together. They ultimately track the body to a mental hospital, where they uncover that the poor are being used as subjects in unethical experiments purportedly to develop vaccines to illnesses such as tetanus and cholera, but something more sinister may actually be afoot. The book leaves the central mystery more or less unresolved — the puppets are arrested but the puppet master remains unidentified (one can only assume since we're dealing with Holmes pastiche that the villain will be revealed to be Moriarty in the second book).
I really think this could have worked as a story that wasn't a Holmes pastiche at all. I suppose Holmes gets butts in seats as it were, but the presence of Holmes wasn't the most interesting thing about the story, and I don't know that he really added much to the story. I would have been fine if it had been simply a mystery novel featuring a female detective in Victorian England. Kronberg was an interesting enough character to have carried the book on her own. In fact, I found her struggles with gender and identity far more interesting than the actual mystery or any hint of potential romance with Holmes. The author raises interesting questions about what it means to be a man and to be a woman, and how qualities traditionally defined as "masculine" or "feminine" both help and hinder Kronberg as she attempts to navigate an oppressive world. Kronberg is precise and crisp when she's dealing with science, but also proves through her relationship with an Irish thief to embrace more human desires with no shame.
I also like that Wendeberg gets into the muck of Victorian society, quite literally. The story opens at a sewage plant and features the aforementioned mental institution and an overcrowded slum as its other main set pieces. Kronberg chooses to live in an impoverished neighborhood rather than someplace more middle-class, and I appreciate that Wendeberg didn't sanitize Victorian London in the way some other novels might have. The stinking chamber pots are in plain sight here. (hide spoiler)]
The novel had some flaws. Some of the scenes felt like sketches where the picture hadn't been fully inked in, and Holmes didn't feel quite right as a character. He was a little too vulnerable, a little too tender at points.
Overall, though, I liked it enough to read the next book.