The brainchild of Proctor Vigdis, the few members of the Ecclesiarchy on Temperance, and a council of senior farmers, Thirdstone was to be the new jewel of the planet. Designed with a desire to push the frontier world into the next phase of development, Thirdstone would serve as its new Ecclesiarchical centre. Rumours hinted that upon completion, the Legion of Twelve might cede full planetary authority to the head of Temperance’s Adeptus Ministorum contingent—Deacon Christof Mannicus.
Yet trouble hampered Thirdstone’s construction, even before the first groundbreaking ceremony. The Sons of Temperance declared the plan an abomination, and the chosen site lay upon the ruins of Askellon’s worst sins. Daily sermons described how building the city upon what they called the “Danestone,” or “Sinful Foundation,” would only hasten the Emperor’s judgement, and that if Vigdis followed through with her plans, the new city would share the same fate as “those that had come before.” Congregations of Sons cultists held up material convoys, and false reports of mind-mould outbreaks slowed construction to a crawl. Anyone who joined the building efforts began receiving threats, although indirectly and never with enough evidence to implicate the Sons. The Bastion Deputies did what they could to keep construction on track, but the cult’s influence, especially with the people of Beacon, made any sort of public repression next to impossible. Eventually, not even the daily protests slowed construction and, after two years, Deacon Mannicus officially opened Thirdstone with a week-long series of blessings and sermons. Weeks after the visitors to the opening had departed, though, every soul in Thirdstone vanished, seemingly overnight.
How it happened remains the frontier world’s most enduring mystery, but all citizens know where they were when news broke of the city’s sudden emptiness. Proctor Vigdis ordered every member of the Legion of Twelve plus a large contingent of Bastion Deputies to ascertain the truth. The Arbitrators found a pristine city with everything in order, but devoid of any living creature. Uneaten meals and lit candles sat inside silent houses. Prayer books and still-smoking censer burners lay within the empty cathedral. Thirdstone was a ghost town, and the Adeptus Arbites and deputies returned to Vigdis without any clear explanations.
The Sons of Temperance poured into the streets of Beacon, their wails of recrimination loud and unfettered, and if not for the dedication of the Bastion Deputies, the Thirdstone calamity might have sparked another societal collapse. On that fateful day, Temperance shifted from a frontier world grasping at the hem of greatness to an Askelline curiosity, especially to the Adeptus Mechanicus, who sent several survey teams to observe Thirdstone and determine, if possible, what became of its populace. Several Inquisitors caught wind of the events as well, but the unpredictability of the Pandaemonium made any signiicant investigations difficult.
In the dozens of years since that day, Thirdstone remained a quarantined zone, as untouched as it was the day everyone disappeared. Proctor Vigdis now fears that any attempts to repopulate the city might result in another tragedy, and many believe that the elderly Arbitrator’s self-imposed seclusion is also a result of the Thirdstone incident. For their part, the Sons of Temperance still preach of their vindication, and their leaders stand on every Beacon street corner with prophecies of more divine retribution to come.