Derby is the largest city in Derbyshire — the county's urban and commercial centre, situated on the River Derwent at the point where the county's character shifts decisively from upland to lowland, from limestone and moorland to the flat industrial Midlands beyond. It is a cathedral city, a manufacturing city, and a city that has always had one foot in the county and one foot out of it. The hills of the Peak District are a different country from here.
Derby's industrial identity runs deep. The Derwent Valley, just north of the city, is home to the earliest factories of the Industrial Revolution — the Lombe brothers' silk mill, Arkwright's Cromford Mill — now a UNESCO World Heritage Site tracing the birthplace of the modern factory system. Rolls-Royce has maintained its principal aero-engine manufacturing operations here since 1908. The city is accustomed to large-scale, methodical production; it is a place that builds things, processes things, and operates at a scale that the moorland villages to the north simply do not.
Within the Book of Thoth Saga, Derby functions as the county's outermost anchor — the urban edge of the world in which Hope's End exists. It is the place that ordinary Derbyshire life faces toward when it faces away from the hills. And in the six weeks following Robert Knight's first major manifestation, it becomes the first registered point in a pattern no civilian in the city has any reason to recognise as one.
Derby does not share the moor. It does not share the limestone. It does not carry the smell of peat or the silence of a valley at night with no traffic and no ambient light except the faint orange glow above Sheffield on the northern horizon. Derby is a city, and the saga's characters experience it as such — as the place where the county's quiet and the county's ordinariness are replaced by the particular quality of urban anonymity. In a city this size, nobody knows you. Nobody is watching. Nobody has noticed anything.
This is, in the context of the saga's concerns, precisely what makes it interesting. The anomaly registered in Derby does not draw attention the way it might in a village. A stranger at a market stall, a coin that is wrong in a way nobody can articulate, warmth where there should be cold — these things pass through a city and leave no mark on its surface. Derby goes on being Derby: the traffic on the A38, the market in the Guildhall square, the jets being assembled in quiet industrial buildings on the edge of the city. Nothing to see here. Move along.
Declan Marsden's description of the Mammon mechanism — it does not take, but makes people reach — is, in a city this size, a description of something that could spread very quickly and remain invisible for a very long time. Derby is the outermost point in the pattern. Whether it is also the starting point, or simply the furthest the reach has so far extended, is a question the pattern alone cannot answer.
