The Beekeeper’s Apprentice is the first in the Laurie R. King’s excellent (IMO) Mary Russell and Sherlock Holmes series. I’ve really liked a lot of the books in this series, especially the ones where Holmes and Russell are caught up in the Great Game rivalries of the time. This book goes on sale pretty often in the UK, where it is £1.89 now, and has been for a few months. It doesn’t go on sale so often in the US, but it’s $2.99 right now (January 7, 2021) at both Kindle and Kobo US.
The Beekeeper’s Apprentice is on sale again, this time for $2.99 in the US, and £1.49 in the UK. The links in the OP just above are still good…