Petropolis Undersink

Petropolis Undersink refers to the lower wards of the hive city of Petropolis on Eustis Majoris, as depicted in Dan Abnett’s Eisenhorn novels. The name denotes the sunken, sub-surface tiers of the hive that lie beneath its more affluent upper spires, comprising older habitation blocks, disused processing works, and service conduits associated with the world’s petrochemical extraction industries.

Conditions in the Undersink are markedly poorer than those of the hive’s upper levels, with overcrowded tenements, failing infrastructure, and limited oversight by planetary authority. Such districts are typically characterised by dense, transient populations, informal economies, and the presence of criminal syndicates and scavenger communities operating largely beyond the reach of formal governance, features consistent with the lower strata of many Imperial hive settlements.

Within the Eisenhorn cycle, the Undersink features as one of the districts of Petropolis through which Inquisitor Gregor Eisenhorn and his retinue conduct enquiries during their investigation on Eustis Majoris, its concealed and disorderly character rendering it a plausible haunt for informants, fugitives, and illicit trade connected to the wider case.