In the far reaches of the Imperium, aboard the Mechanicus exploratory vessel "Pax Mechanicum," Magos Explorator Varen leads a diverse contingent of Imperial forces on a mission of discovery. Their destination: an uncharted tomb world known as the Ossuary of Nocturne, rumored to hold ancient technological marvels and untold secrets. As they descend upon the desolate surface, the exploratory team soon realizes they are not alone.
Awakening the dormant systems of the Ossuary, the Imperials unwittingly stir ancient guardians and long-buried horrors from their slumber. Caught amidst a waking nightmare, Varen must rally his forces, including Skitarii soldiers, Astra Militarum troopers, and a squad of Adepta Sororitas, to fend off the relentless onslaught of mechanized horrors and malevolent entities.
As the battle for survival unfolds, tensions simmer among the diverse Imperial factions, each with its own agenda and priorities. Amidst the chaos, Varen struggles to maintain cohesion within his contingent while deciphering the secrets of the Ossuary. With each passing moment, the ancient constructs grow stronger, their malevolence threatening to overwhelm the Imperials.
In a desperate bid to turn the tide, Varen delves deeper into the Ossuary's mysteries, uncovering forgotten lore and ancient technologies. But as he unlocks the secrets of the past, he also awakens darker forces that challenge the very fabric of reality itself.
With time running out and the Ossuary's defenses closing in, Varen and his comrades must make a final stand against the encroaching darkness. In a climactic battle for survival, the fate of the Imperium hangs in the balance as they confront the true horrors lurking within the depths of the Ossuary of Nocturne.