Last, we're told, in the tetralogy (Empire of Unreason, 2000, etc.) set in an alternate 17th century where science, alchemy, and magic all work, and the world is threatened by insubstantial, malevolent entities called Malakim. Since its inception with Sir Isaac Newton and an alchemical war between Britain and France, the plot's wandered far. Here, once again, the world must be saved: step forward Ben Franklin, Newton's former apprentice, French scientist-magician Adrienne de Montchevreuil, and Red Shoes the Choctaw shaman. As before: imaginative but far removed from any recognizable reality. Still, if you've hung in there this long, you'll want to complete the journey.