The winter of 1894 began not with a flurry of snow, but with a stagnant, suffocating fog that seemed to seep through the very masonry of Baker Street. Sherlock Holmes had been in the grip of a corrosive melancholia for a fortnight — and into this glacial stasis walked a man who was being erased from reality itself. A Keeper of the Royal Observatory, whose wife had been vibrated out of existence, whose desk had dissolved into perfect, pristine floorboards, whose life was being edited by a scientist who believed he could silence the frequencies of human existence.

The London of 1895 was a city of ghosts, draped in a shroud of soot and secrets. Into the acrid air of Baker Street walked a woman whose father, a legendary architect, was physically transforming into cold, unyielding marble. A "Memory Palace" in a secluded Highgate valley was aging centuries in a single afternoon, controlled by the mysterious Count de St. Germain. Holmes must confront a fanatic who has mastered the "solvent of years" to preserve the world as a gallery of frozen, stony moments before the ticking clock of reality stops forever.