"If you go to that Emperor-forsaken place, take their advice: keep a bullet. Always keep one. Not for them, you understand -- no, keep it for yourself."
- —Investigator Verger Bor
Fenksworld is a small, grimy Imperial Hive World located to galactic coreward in the Josian Reaches sub-sector of the Calixis Sector. Fenksworld serves as a substation service depot of the Navis Imperialis' Battlefleet Calixis. It is suggested that many cults and other "secret parties" test their influence on the Fenksworld population, using it as a manageable test bed before moving on to dominant worlds like Scintilla and Malfi.
Chaos Cults and cult activity certainly fester here. Fenksworld's most notable feature is its Library of Knowing, one of the Calixis Sector's most comprehensive sources of data outside the Prol System. The Library of Knowing’s most significant attribute is that it is run under the administration of the planetary governor and exists outside general Imperial jurisdiction.
The Calixian Conclave of the Inquisition has made several (subtle) attempts to close the Fenksworld library down, due to its esoteric contents. The library remains a "family run" enterprise, overseen by the Planetary Governor's family, the mercurial noble House Vaahkon.
The world is dominated by the primary hive city of Nova Castilia and its two subordinate hives, the subterranean Magnagorsk and the sprawling hive of Volg that stretches for hundreds of square kilometres across Fenksworld's acidic salt-fens.
History

View from the spires of Fenksworld's primary hive city of Nova Castilia.
To most outsiders, Fenksworld has a reputation as a grimy, roughshod place, a Hive World that, while notoriously independent in sector politics, is seen as lacking the significance or sheer size of the likes of Scintilla or Malfi. The truth of the matter is that Fenksworld's independence and measure of self-sufficiency is bought at a price, and its bustling façade hides a number of dark secrets.
The Fenksworld that most outsiders see is the hive city of Nova Castillia -- a vast towering edifice of sky-piercing spires and busy supply depots, noble enclaves, covered hab-stacks and bustling neon-lit entertainment 'burgs. Although a little ramshackle and dirty, it is not unlike many other hives across the Imperium. While Nova Castillia houses much of the planet's famously mercurial ruling elite and the bulk of the planet's population, what is not widely realised is that it also holds two subordinate hive cities in a merciless grip to ensure this position, hives that most off-worlders, if they are fortunate, never see.
The first, Magnagorsk, sinks deep into Fenksworld's crust. Heavily industrialised, it is a hellish place of molten metal and volcanic fires, where warship armour is forged and poisonous ash fumes the air. The hive exists purely to serve the Battlefleet Calixis port anchorage in high orbit. The conditions are so harsh that a native of Gunmetal City or The Lathes might count themselves fortunate on seeing them.
Magnagorsk is controlled by the fractious and pitiless foundry guilds. To them labour and metal are the only coins of the realm, and one guild master would think nothing of sabotaging or murdering his rivals, or kidnapping entire work gangs to help meet his production quotas. Life is cheap in Magnagorsk, violence commonplace and death and maiming everyday hazards, but the helots that toil thanklessly there know that it could be worse; they could be exiled to Volg.
Rather than towering above or delving into the earth, Volg sprawls for hundreds of square kilometres like a vast cancer of corroded gantries and phosphor-lit domes that have spread over Fenksworld's acidic salt-fens. The sprawl itself is made up of vast moisture-traps, reprocessing plants, waste-biomass recycling reservoirs and the mad clusters of stilt-supported shantytowns that cling to them. The simple truth is that without these facilities' output, famine, pollution and poisoned water would destroy Fenksworld in a few short standard years -- the toil of millions is needed to keep billions more alive.
Named by some as the vilest and most misbegotten place in the whole Calixis Sector, the toxicity and terrible conditions in Volg are at the very limit of human survivability. Matters are made worse by Fenksworld's many unutterably lethal and horribly mutated native creatures.
Volg was initially set up as a vast open penal colony for Fenksworld and the surrounding sub-sector, and the inmates were left to found their own societies and to make what they could of their lives -- so long as clean water and protein flowed up-hive to where it was needed. Control was further maintained through the trade in cheap arms and vital supplies, and it transpired that Volg's population was mostly too occupied trying to survive to attempt escape or plot revolt.
Over the centuries Volg, to the surprise of many, prospered and became a hive city in its own right with a population in the tens of millions. While new inmates (or "clean meat" as they are known in local parlance) are sentenced to exile there still, the majority of its inhabitants are now freeborn, some "six generations in the Volg" and free to leave -- if they can afford the exorbitant passage out. Life in Volg is violent, anarchic, blighted and often very brief, but as for the Volgites themselves, they are born survivors. Few Death Worlds breed hardier or more ruthless fighters.
The Library of Knowing
The Library of Knowing is one of the greatest repositories of record, scholarship, and wisdom in the Calixis Sector. A vast assemblage of works acquired by Lord Militant Golgenna Angevin's coterie of scholars, scribes, and advisers during the Angevin Crusade and from his private collections, the Library of Knowing is an enduring relic of the foundation of the sector. It was one of the liberator's dying indulgences that gave the Library of Knowing its unique status that has seen it remain to this day under the authority and care of House Vaahkon, the ruling house of Fenksworld.
Angevin's ink-stained minions assembled a wondrous collection of tomes, data-cores, and art from across the Imperium, including illuminated works from distant Terra, loose parchments by forgotten authors, and curled scrolls of ancient lore plundered from vaults and Renegade worlds.
It is this collection that forms the core of works held in the Library, though a great deal more has been added over the centuries by House Vaahkon and by numerous private donors, state seizures, and bequests. It is open to any who can bribe, intrigue, or inherit his way onto its exclusive list of readers.
The library building itself is a vast vertical drum of worn metal that juts from the spires of Nova Castillia. Its internal spaces are divided by pillars and walls of stone, and its open galleries crossed by gantries and walkways of tarnished brass. Some within the Inquisition are certain that the Library holds proscribed works in its secret stacks despite repeated searches that have turned up nothing of overly heretical note.
This supposition is made all the more likely as it is the known birthplace of the tainted Ateanist philosophy. Curiously, the library has remained largely untouched in the face of Inquisitorial disapproval in spite of its dubious association with this proscribed, daemon-influenced tradition, leading many to believe the library has powerful patrons beyond just the mercurial House Vaahkon. Perhaps there is even someone within the Holy Ordos itself.
Departmento Cartographicae Planetary Database
- Galactic Position: 1056/45/CS/H.
- Population: 22 billion
- Geography: Extremely cold nights, extremely hot days at the polar caps and temperate climate at the equator. Fenksworld possesses four mountainous and rocky continents separated by polluted seas and oceans. On the southern polar continent lies Magnagorsk Hive, at the northern polar cap is Nova Castilla, on the western continent is Volg Hive, the capital city of the world, and on the eastern continent lies the ruins of Hive Akelia, which collapsed solar decades ago. Fenksworld has no moons but there is a major network of orbital docks located in geostationary orbit above Nova Castilla to service the vessels of the Imperial Navy's Battlefleet Calixis.
- Government Type: Imperial Adeptus Terra
- Planetary Governor: Josian Reach Sub-sector Governor Pas Palacius
- Adept Presence: Adeptus Terra, Adeptus Administratum, Adeptus Ministorum, Adeptus Astra Telepathica (Astropathic Choir at Nova Castilla), Adeptus Arbites (high Arbitrator to civilian ratio).
- Military: Volg Volunteers (local Planetary Defence Forces; medium quality force, based at Volg Hive), numerous Volg Regiments (1-414th; medium/high quality force, based at Volg Hive), Castillian Finest (local Planetary Defence Forces; high quality force, based at Nova Castilla).
- Trade: Main source of manpower and labour in the sector's Josian Reach. Abundant with various underground factories and refineries dedicated to everything from ore processing to water purifying.
- Contact with Other Worlds: Stable Warp routes link Fenksworld to Acreage and Zillman's Domain.
- Tithe Grade: Exactus Extremis.
Sources
- Dark Heresy: Core Rulebook (RPG), pg. 324
- Dark Heresy: Creatures Anathema (RPG), pp. 55, 57
- Dark Heresy: Disciples of the Dark Gods (RPG), pp. 47, 66, 73, 84, 96, 132, 135
- Dark Heresy: The Inquisitor's Handbook (RPG), pp. 25, 60, 111, 113, 116, 119, 121-122, 125, 129-130, 171
- Dark Heresy: The Radical's Handbook (RPG), pg. 138