London, 1851. A young Kazakh engineer, Yerzhan, arrives at the Great Exhibition in the Crystal Palace with a mechanical calculator. His guardian is Kazakh, a retired military intelligence officer versed in the ancient knowledge of the steppe baksy. Their invention draws the sinister Mr Cromwell — an ageless creature with a frozen predatory grin, hiding among humans for four centuries. The investigation leads Kazakh to a grim house on Half Moon Street for a confrontation with age-old evil.