Not one of Powers' best books, it's a story of various people in 19th century London haunted by ghostly figures referred to sometimes as vampires, but largely unrelated to the ones we know. The rules surrounding the creatures and how they're dealt with or worked around are hazy at best, and the eventual climax isn't very satisfying. It's sort of a sequel to The a Stress of Her Regard, and if you enjoyed that one then you'll probably like this one (I don't rank Stress among his best, either). But as a fan of his more tightly-plotted novels, I don't think this one measures up.