The book starts out as a detective thriller, as a police officer infiltrates a cabal of anarchists, and the story gets more and more outrageous until it seems to become farce, but then it takes a very dark turn, and finally is maddeningly opaque at the close of the narrative. No wonder Chesterton subtitled the book “A Nightmare“. Yet, the story pulls the reader along without let-up -- I never considered not finishing it, as lost as I might be.