It is a period of civil war. Rebel spaceships, led by the former imperial Warmaster Horus, are beginning their campaigns against the corrupted Imperium of Man.
Against them, the nigh-immortal Emperor waits on his Golden Throne. Allied with him are the four Chaos Gods, eldritch nightmares thirsting for human suffering. The Space Marines, once the Imperium's finest soldiers, are divided. The Emperor has gathered around him those of his sons - the Primarchs - that would not betray him, among them Konrad Curze, the Night Haunter of the Eighth Legion. The universe is full of evil and doubt, and only Horus and his armies can hope to save humanity from the laughter of dark gods.
Yet the Emperor too wishes to silence that laughter, and to make his power as the supreme god be recognized. It is for that reason that he sends Curze on a mission so secret that not even his closest sons, Lorgar and Dorn, know about. But in shadows this deep, there is room enough for many heroes, or monsters, to leave their unremembered mark.
The screams and pleas of the innocent will have no effect - not anymore. The age of debate and enlightenment is over. The dream of empire has ended.
The nightmare has begun.