This is a legendary era. The galaxy is on fire. The Emperor's great plan for humanity has been destroyed. His beloved son Horus turned from his father's light and embraced Chaos. His armies, the mighty and fearsome Space Marines, are embroiled in a brutal civil war. Once these accomplished warriors fought side by side as brothers, protecting the galaxy and returning humanity to the light of the Emperor. Now they are separated. Some of them remain loyal to the Emperor, while others have sided with the Warmaster. Among them rise the commanders of thousands of Legions - the primarchs. Majestic superhuman beings, they are the crowning achievement of the Emperor's genetic science. The victory of any of the parties entering the battle with each other is not obvious. The planets are burning. On Istvaan V, Horus struck a brutal blow, and the three loyal Legions were all but destroyed. The war has begun: a confrontation whose fire will engulf all of humanity. In place of honor and nobility came betrayal and treason. Assassins lurk in the shadows. Armies are gathering. Everyone must choose one side or die. Horus prepares his armada. The target of his wrath is Terra itself. Seated on the Golden Throne, the Emperor awaits the return of his wayward son. However, his true enemy is Chaos, the primordial force that wants to subject humanity to its unpredictable whims. The cruel laughter of the Dark Gods echoes the cries of the innocent and the pleas of the righteous. If the Emperor fails and the war is lost, suffering and damnation will await everyone. The era of knowledge and enlightenment is over. The Age of Darkness has arrived.