At the very birth of the Imperium of Man, fully half of the Emperor's most trusted Space Marines Legions turned against him in a bitter civil war. Brother fought brother, and Mankind stood upon the very brink of extinction. Ten thousand years after their defeat, those same traitors still launch their Black Crusades out of the Eye of Terror, intent upon nothing less than the utter destruction of the Imperium and the death of its weakling Emperor.

Now and forever they had become Chaos Space Marines, despised and feared as traitors and heretics throughout the galaxy.

Worse still, the path to immortality offered by the Chaos gods led through a hell of death, mutation and madness. Daemonhood awaited them at the end of the road, followed by an eternity as slaves to darkness.