The British Empire is at the height of its power by the end of the 19th century. Queen Victoria reigns over a global empire where the sun never sets. However, in its shadow, the underworlds merge, teeming with all sorts of light-shy creatures. Sherlock Holmes has already witnessed the ruthless criminal Moriarty making a pact with demons. But what the "Fathers of Realms," an obscure English secret society, intend to do far surpasses this monstrosity. They aim to grant the powers of darkness permanent access to the human world. To achieve this, they are using Lynn Redstone as their extended arm, a young woman with almost superhuman powers.