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.

On the 13th day of Secundus, the bombardment of Terra began. With the solar defences overcome through the devastating strength of the Traitor armada and the power of the warp, Horus launches his assault on the Throneworld in earnest. After withstanding a ferocious barrage of ordnance, an immense ground war commences outside the Palace, with every inch gained paid for in the lives of billions.

The Shattered Legions crew of the Sisypheum, broken and at the end of their endurance, find themselves divided - torn between following their resurrected captain on a suicidal mission or obeying orders to return to Terra and rejoin their Legion brothers. Following a series of garbled messages intercepted by the Kryptos, the divided warriors descend to the shattered surface of Luna. Here, their bonds of loyalty, duty, and their devotion to one another will be tested as ancient horrors of the earliest days of gene-manipulation are unleashed, and a long-buried secret is revealed.

Exile to the miserable world of Sedh, the disgraced Necron Lord Oltyx is consumed with bitterness. Once heir to the throne of a dynasty, he now commands nothing but a dwindling garrison of warriors, in a never-ending struggle against Ork invaders. Oltyx can think of nothing but the prospect of vengeance against his betrayers, and the reclamation of his birthright. But the Orks are merely the harbingers of a truly unstoppable force. Unless Oltyx acts to save his dynasty, revenge will win him only ashes.

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.