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. Yet on the whole, men and worlds are flocking to Horus's Coalition, driven by both the Warmaster's charisma and the Emperor's tyranny.
Horus and his Primarch brothers know it is unlikely to be enough. Frontier reports have reported ethereal creatures of an unknown nature appearing and massacring whole populations. The Warmaster is not taking this threat lightly, and so he has resolved to form a new force to combat this threat most dire, as part of an improbable alliance. Some battles, however, are best fought in silence. And some lights shine brightest in the darkest night.
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.