Joan Wolf is one of my favorite Regency romance authors, but she also wrote two medieval mysteries many years ago. Now both are on sale for $1.99 in the US, and discountable at Kobo. There are definitely romance elements in them, but I think of them more as mysteries, and SYKM lists them too. I enjoyed both, and wish she had written more…
The Poisoned Serpent is on sale again at Kindle US for $1.99, but not at Kobo US. The link in the OP just above is still good. And, although the first book in the series is not on sale, at least as of now, it is in KU, so if you have that, you can read them in order without paying a lot.