The sixth decade of the Great Crusade begins. The fleets and armies of the Lord of Men pierce the Galaxy, bringing the Imperial Truth to thousands of worlds. Expansion has proceeded at a rapid pace, but now is the time to gain a foothold in new territories. However, the Master of Mankind demands that the boundaries of the Imperium be pushed further into the unknown. He entrusts four Primarchs with the dangerous task of conquering the worlds of Occlude Noctis. There are hundreds of star systems there, located on the far side of the Great Northern Warp Storm, whose presence is causing disturbances in the empyrean and consuming the guiding light of the Astronomican. The anomaly is impenetrable even to the psionic gaze of the Emperor, but Rogal Dorn leads the Seventh Legion into the very depths of this cosmic darkness. Cut off from his allies, the Lord of the Imperial Fists battles an enemy the likes of which have never been seen before. Dorn will need all his unmatched talent as a strategist and indomitable will to conquer the darkness in the name of the Lord of Men.