It is London, 1756. In his Bloomsbury attic sits Dr Sabian Blake - astronomer, scientist, and master of the Kabbalah. Dr Blake is in possession of the Nemorensis, an ancient leather-bound book that holds the secrets of the universe. Scribbled into one of its margins is a mysterious prophecy and deciphering it could prove the key to saving London from a catastrophic fate. But there are others interested in the Nemorensis too, for more sinister reasons . . .