Dr Sabian Blake – astronomer, scientist and master of the Kabbalah – possesses the Nemorensis, an ancient, leather-bound book which holds the secrets of the universe. Leafing through it, he reads a mysterious inscription: 'Wormwood… the bright star shall fall from the sky... and many will die from its bitterness.' Deciphering the prophecy could prove the key to saving London from a catastrophic fate. But there are others interested in the Nemorensis too – for more sinister reasons. Blake and his serving maid Agetta Lamian soon become enmeshed in a web of sorcery, as agents of both good and evil battle to possess the book and gain its power...