Flashback, by Nevada Barr
Another pulse pounding Anna Pigeon-in-peril story. Interleaves a story of Anna's ancestor living at Fort Jackson, when it was a post-Civil War prison, with the modern day story of Anna as a ranger at the same Fort, now an NPS site.
Good story, new developments in Anna's life, and plenty of painful scrapes and escapes, along with an interesting and complicated plot. Good read! Now, back to Mithgar, the not-quite-Middle-Earth land from Dennis Mckiernan.