This was okay, but just okay. As much as I wanted to care about the lead character, I have to say it was hard, and not because of any of her behavior, but I think it was because of the writing style. It just felt really workmanlike, very straightforward, with no nuances. You were never in doubt about how the character felt about anything that happened in the book, never left guessing, so I felt kind of disengaged from the story overall. The side character of Maria Kalderash had some potential, despite the fact that we knew much less about her, perhaps because we knew less about her, now that I think about. At least I had to have an internal conversation with myself about why she was doing what she was doing sometimes. Sophie was a bit of a caricature. Honestly, it was hard to stay focused on it. I was reading it for a book club and that is probably the only reason I felt motivated to finish it.
The plot had potential, about a woman with a dark past as essentially a snake-oil-charmer fraud who had been making lifethreatening alchemical substances for the rich, bored, and vain and is trying to make up for it and put that past behind her forever. But that backstory was not very well-developed and it was confusing to keep track of it. There were two very similar male authority figures who at times seemed both like the villians, but by the time the truth is revealed, the two men seem so similar, it's been almost difficult to tell the difference between them.
Basically, a lot of underdeveloped plots and characters, perhaps in part because the author (or maybe the publisher) was trying to keep the book pulpy short and snappy. But it did a decent story idea no justice.