A body is found crushed to death in the London snow. There are no footprints anywhere near it. It is almost as if the man was killed by the air itself. Sherlock Holmes and Dr. Watson find themselves travelling to Scotland to meet with the one person they have been told can help: Aleister Crowley. As dark powers encircle them, Holmes’ rationalist beliefs begin to be questioned. The unbelievable and unholy are on their trail as they gather together the most accomplished occult minds in the country: Dr John Silence, the so-called “Psychic Doctor”; supernatural investigator Thomas Carnacki; runic expert and demonologist, Julian Karswell... But will they be enough? As the century draws to a close it seems London is ready to fall and the infernal abyss is growing wide enough to swallow us all.