This was a perfectly acceptable take on The Fall of the House of Usher, taking the basic frame narrative and adding character backstory, setting, proper plot, and underlying explanation for the weirdness in the original Poe story. The first half, when we were learning about the culture of Galatia, the history of Alex Easton and Denton, and meeting Miss Potter (who was a delight), was very strong, and I was having a great time. But when the actual mystery of Madeline's weird behaviour was being explored, I didn't find it very mysterious. I'd guess basically everything long before Easton and Denton and Miss Potter figured it out. There was a pleasing little moral dilemma that had be resolved, and which I think was treated effectively. 

But, at its heart, I felt like there was a conflict between what Kingfisher does best---light fluffy banter---and what this book was aiming to be: horror. The reduced amount of banter made the narrative less fun, while the wit in dialogue and narrative that Kingfisher, by virtue of being a witty writer, could not entirely expunge, made the horror bits less scary. Which is fine, for me---I don't like being scared---but I do wish there had been just a bit more fun and less vibes in this book. I read The Fall of the House of Usher to make sure I was fully up on the source material, and got so bored and impatient with the emphasis on vibes and atmosphere to the exclusion of plot, that even the much more measured quantity of that which Kingfisher included here just felt like more of the same, which made me restless.

This is very personal, and highly related to my own previous experience with Kingfisher, my own opinions about the proper proportion of vibes in Gothic horror books, and my own reaction to Poe.  I think Kingfisher accomplished well what she set out to do, and I'll read more of her horror, now that I know it's not actually that scary, because I'm always up for some Kingfisher. I just kind of miss her fluffy bantery romps.