In the grim darkness of the far future, an Inquisitor of the Imperium finds themselves stranded aboard an impossible discovery: a colossal monastery-battleship that vanished millennia ago, now drifting silently through the Caligari Sector. After their vessel is shot down by the derelict's defenses, the Inquisitor must navigate the ship's labyrinthine, corrupted corridors while battling the twisted horrors that have taken root within its hull. What begins as a routine investigation into a ghost ship transforms into a desperate search for answers, as the Inquisitor pieces together the enigmatic circumstances of the vessel's ancient disappearance and confronts the insidious forces that have kept it hidden from the galaxy for five thousand years. Tasked with purging heresy and mutation wherever they emerge, the player must survive the darkness dwelling in this forsaken relic while uncovering secrets that could shake the foundations of Imperial faith.