I hate to say this, but this book just didn't capture me. I enjoy Lady Petra as a fun detective and the feminist vibes that she displays, but the plot just was too jumbled and slow for me. I felt like many of the twists were obvious and a bit circuitous. The big twist at the end was a true shocker, but by that point I had lost a lot of interest.  I think that this was more my expectations for this series than the series itself, but I just was left wanting more from the characters.  There were a LOT to keep track of, and they were referred to so many different ways (title, first, last, nicknames) that it did become confusing especially listening to the audio.  That also made the twists a little less impactful when you're trying to remember who is who and related to whom. I was also confused about the spy plot, because it seemed like everyone knew about the double agents, but also it was a deadly  secret? I don't know, maybe we as the readers knew too much at the start and then the story lagged a lot up until the end.

I think lovers of historical mystery will enjoy this, if they enjoy mysteries involving the upper classes.

Note: The audiobook narration is good, though most of the male character narration wasn't my favorite.