Tantalus - Pyroclast-Gamma-9: Pyroclast-Gamma-9 was an industrial facility and promethium refinery in Tantalus' extreme north, set amid sharp-edged rocks, tumbledown crags and coarse tundra.One of a string of similar facilities scattered across these latitudes, it was a sprawling complex, with numerous buildings, stations, and supply dumps spanning several square kilometres in size, although much of its uninhabited infrastructure (such as the chemical storage tanks) was actually buried deep underground beneath the steel domes, pipe-farms and dull ferrocrete blockhouses that make up the facility.During full operations, the area was staffed by a crew of Departmento Munitorum functionaries and technomats, their attendant servitors and a sizable workforce of convict labour kept in check through the use of pain-inducing punishment collars and the overseer's lash.Unfortunately, the crisis had seen tragedy and death come to the area. In the days before Tantalus' fall, vanguard organisms of the Tyranid swarm had attacked, and many of the technomats had already fled or been killed, leaving the prisoners out of control and the station's servitors on emergency protection programming, but without any form of central control.Hormagaunts and Termagants already lurked in the shadows of the nearby ravines and had forced their way within several of the buildings, butchering everyone within, while the dark-winged shapes of Shrikes arced across the cold skies in increasing numbers. The swarm was on its way, and Pyroclast-Gamma-9's existence could now be measured in solar hours.The area around Pyroclast-Gamma-9 was sub-arctic tundra, and the terrain was riven with spars of granite, broken ground, steep crags, scree hills, and muddy sinkholes worsened by industrial traffic and chemical pollution. The air was cold and thick, heavy with the stench of burning chemicals and drifts of black smoke.The light levels were low -- noon on Tantalus corresponded to a bright twilight on most other Human-habitable worlds. While the skies to the polar north were a harsh icy grey, the southern horizon had already been swallowed by a rolling purple-black maelstrom, shot through with unnatural veins of cankerous yellow -- the atmosphere of the moon itself was being changed and devoured by the Tyranid spores.Dotted around this bleak natural landscape were the obvious signs of the Imperium's hand in exploiting the moon's resources in the shape of metal grillwork pathways, strings of battered lumen globes, machine workings, and the brutal scars of past excavations.The tracks of heavy vehicles had churned up the ground. The architecture in evidence was brutally functional and prefabricated in origin, constructed of harsh square-sided ferrocrete bunkers stamped with codesigns and Departmento Munitorum admissions to workers to obey and remain productive. Looming iron-black engines and rusted pipe-work crisscrossed the landscape.Here and there were signs of then-recent violence and destruction, machinery overturned, areas blackened by fire (some still smoking) and the grey bodies of dead convict-workers. Many had been stripped of their flesh by the claws and fangs of Tyranid vanguard organisms, but others bore evidence of gunshot or stab wounds caused by other Humans.Tantalus had almost succumbed to the Tyranids' shadow. Vox communication and auspex tracing on its surface had become almost impossible. Teleport access was also impossible, and any craft that approached the moon's near orbit and upper atmosphere were subject to swift attack and destruction by the Tyranids.A single Drop Pod fired in from high orbit had the best chance of evading detection, and that's where the Deathwatch Kill-team came in to begin the search for Magos Vyakai and his precious data.