Two centuries ago, the Imperium of Man and the upstart Tau Empire fought to a standstill in the Damocles Gulf. Now, as the 41st millennium draws to a close, the tau have returned. As the world of Agrellan falls under attack, the White Scars and Raven Guard rush to its defence, but with the skilled Commander Shadowsun leading the alien forces, the Space Marines and their allies are hard pressed. Kor'sarro Khan, Huntmaster of the White Scars, swears that he will win the day in the most direct way possible – by taking Shadowsun's head.

After seven years of bitter war, the end has come at last for the conflict known infamously as the Horus Heresy. Terra now lies within the Warmaster’s sights, the Throneworld and the seat of his father’s rule. Horus’ desire is nothing less than the death of the Emperor of Mankind and the utter subjugation of the Imperium. He has become the ascendant vessel of Chaos and amassed a terrible army with which to enact his will and vengeance. But the way to the Throne will be hard as the primarch Rogal Dorn, the Praetorian and protector of Terra, marshals the defences.

After seven long years of conflict, the Horus Heresy nears its end. But now, as the Warmaster Horus marches on Terra to rip his father from the Throne, the seat of the arch-traitor’s power lies empty. Cthonia, a world once dominated by brutal murder-gangs, is occupied by the Emperor’s praetorians—the indomitable Imperial Fists. For the Sons of Horus, this outrage demands a reckoning.

The Blood Angels Chapter of Space Marines is under threat. Having obliterated all human life in the Red Scar region of space, the largest tendril of Hivefleet Leviathan ever seen in the Imperium has converged and is making relentlessly for Baal. To face this awesome foe, Commander Dante has called upon the Successor Chapters of the ancient Ninth Legion. The Sons of Sanguinius gather in numbers not seen since the dark days of the Horus Heresy.

The Cadian Gate is broken, and the Imperium is riven in two. The might of the Traitor Legions, kept shackled for millennia behind walls of iron and sorcery, has been unleashed on a darkening galaxy. Among those seeking vengeance on the Corpse Emperor’s faltering realm are the Death Guard, once proud crusaders of the Legiones Astartes, now debased creatures of terror and contagion.