A Step So Grave is the thirteenth (2018) in the Dandy Gilver series by Catriona McPherson. It has dropped to $2.99 at Kindle and Kobo US. I've read and liked some of the earlier titles in this series, but the later titles tend to be pretty expensive in e-book in the US, and so I haven't kept up with the series all that much. So it's nice to see one on sale.
Kindle US:
https://www.amazon.com/dp/B07PVYF24H
Kindle US/Smile:
https://smile.amazon.com/dp/B07PVYF24H
Kobo US:
https://www.kobo.com/us/en/ebook/a-step-so-grave-1