Put a fedora hat and worn leather jacket on Joan Markel, place her in the dusty rows of Frank H. McClung Museum's skulls, bones, books and spooky artifacts, and you have the makings of a George Lucas-like blockbuster movie sequel. Call the first one "Tennessee Markel and the Treasure of the Lost Map." Well, maybe that's a little over the top. But you get the notion. Markel is a librarian and an archaeologist with a furious heart for finding the Civil War history of Knoxville. She has uncovered a doozie. Capt. Orlando Poe, architect of Union fortifications in Knoxville during...