It is the winter of 1893, and in London the snow is falling. It is falling as Gideon Bliss seeks shelter in a Soho church, where he finds Angie Tatton lying before the altar. His one-time love is at death's door, murmuring about brightness and black air, and about those she calls the Spiriters. In the morning she is gone. The snow is falling as a seamstress climbs onto a ledge above Mayfair, a mysterious message stitched into her own skin. It is falling as she steadies herself and closes her eyes. It is falling, too, as her employer, Lord Strythe, vanishes into the night, watched by Octavia Hillingdon, a restless society columnist who longs to uncover a story of real importance. She and Gideon will soon be drawn into the same mystery, each desperate to save Angie and find out the truth about Lord Strythe. Their paths will cross as the darkness gathers, and will lead them at last to what lies hidden at the house on Vesper Sands.