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.

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.

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.

Of all the Emperor’s sons who fell to Chaos, it is perhaps Magnus the Red whose tale is the most tragic. Sanctioned because of his desire for knowledge, chastised, judged, and shattered to his very elements – there is much for the Crimson King to feel vengeful for. Yet revenge is not the only thing that draws him to Terra alongside the Warmaster’s besieging armies. He seeks something, a fragment, the missing piece of himself that lies within the most impregnable place on the planet – the inner sanctum of the Imperial Palace.

Lord of Chemos and bearer of the Palatine Aquila, Fulgrim, primarch of the Emperor’s Children, is determined to take his rightful place in the Great Crusade, whatever the cost. A swordsman without equal, the Phoenician has long studied the art of war and grows impatient to put his skills and those of his loyal followers to a true test. Now, accompanied by only seven of his finest warriors, he seeks to bring a rebellious world into compliance, by any means necessary.