The war for the fate of mankind blazes on. Though the outer defences have fallen, the walls of the Palace itself remain inviolate as Rogal Dorn, the Praetorian of Terra himself, uses every known stratagem and ploy to keep Horus' vast armies at bay. In Perturabo, the Traitor siegebreaker, Dorn faces an adversary worthy of his skill. A terrible, grinding attrition ensues. The crucial battle for the Lion's Gate spaceport is at the heart of this conflict. With it in their possession, the Traitors can land their most devastating weapons on Terran soil. Dorn knows it must not fall.

The Traitor Host of Horus Lupercal tightens its iron grip on the Palace of Terra, and one by one the walls and bastions begin to crumple and collapse. Rogal Dorn, Praetorian of Terra, redoubles his efforts to keep the relentless enemy at bay, but his forces are vastly outnumbered and hopelessly outgunned. Dorn simply cannot defend everything. Any chance of survival now requires sacrifice, but what battles dare he lose so that others can be won? Is there one tactical stroke, one crucial combat, that could turn the tide forever and win the war outright? 

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 a series of victories, the Imperial forces are on the back foot once more. The power of Chaos is rising, the Traitors gain ground, and all hope seems lost. Can Terra endure? 

The Inner Walls are breached. Traitor vanguards tear towards the heart of the Palace, sensing victory. Desperate gambits are attempted: an unwilling saint is released into the ruins, as well as an enthusiastic sinner. A black sword rises, forged from spite, ready to create a legend. But amid the slaughter, Jaghatai Khan, Warhawk of Chogoris, prepares to launch the most audacious strike of the conflict. His goal is nothing less than the liberation of the Lion's Gate space port. 

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.

For long years, the Horus Heresy has ground on. Now, the Death Guard have been sent to begin the final battle. But Mortarion and his sons must face their gravest challenge first - for Nurgle has claimed them as his own, and he will not be denied.... The skies darken over Terra as the final battle for the Throne looms ever closer.... As the Traitor primarchs muster to the Warmaster’s banner, it is Mortarion who is sent ahead as the vanguard of the Traitor forces. But as he and his warriors make way, they become lost in the warp and stricken by a terrible plague. 

After a long and gruelling conflict, the traitors at last close upon Terra. But time is dwindling for an attack. Both Guilliman and the Lion are returning with all haste, and their armies could turn the tide. The hosts of the Warmaster must unite, for only then can they attack the Throneworld itself. While Mortarion is sent on ahead as the fleet’s vanguard, it falls to Lorgar and Perturabo to marshal Fulgrim and Angron, both now elevated to daemonhood and perhaps beyond even the will of the Warmaster to command.

Colonel-Commissar Ibram Gaunt spent a year fighting as part of the underground resistance on the enemy-held world of Gereon. When he left, he promised that he would bring the forces of the Imperium to liberate Gereon's citizens from their oppressors. Now he has returned, a crusade army at his back, but he finds a world devastated by war and a people irrevocably damaged by the taint of Chaos. Now Gaunt must fight to save Gereon not only from the enemy, but from the Imperium itself.

In the void and upon the worlds of Greater Ultramar, the battle for the Imperium continues. Intent on rebuilding his home realm and using it as a base to reconstruct the ravaged stellar empire of mankind, the returned primarch, Roboute Guilliman, proceeds with his war to drive Mortarion and his Death Guard Traitor Legion from the domain of the Ultramarines. But when Guilliman brings his brother to battle upon the diseased plains of Parmenio, the intervention of a greater power in their fraternal struggle threatens to upend the Imperial Regent’s understanding of the galaxy. 

The paths of Roboute Guilliman and his fallen brother Mortarion bring them inexorably together on Iax. Once a jewel of the Imperium, the garden world is dying as the plans of the Lord of Death to use it as a fulcrum to drag the stellar realm of Ultramar into the warp come to deadly fruition. While Guilliman attempts to prevent the destruction of his kingdom, Mortarion schemes to bring his brother low with the Godblight, a disease created in the Cauldron of Nurgle itself, made with the power to destroy a son of the Emperor. 

The time has come for Leman Russ, primarch of the Space Wolves, to fulfil his vow and attempt to stop Warmaster Horus before he breaks through to the Segmentum Solar. In the face of opposition from three of his brother primarchs, Russ withdraws the Space Wolves legion from Terra and makes all haste for Horus’ position. Reports from Malcador the Sigillite’s agents suggest that Horus is utterly changed and infused with a diabolical power so great that no man can stand against him.

Fell times have come to the galaxy. Cadia has fallen, destroyed by the onslaught of Chaos. A Great Rift in the warp has opened, and from its depths spew daemons and the horrors of Old Night. But all hope is not lost… A hero, long absent, has returned, and with him comes the wrath of the Ultramarines reborn. Roboute Guilliman has arisen to lead the Imperium out of darkness on a crusade the likes of which has not been seen since the fabled days of the Emperor. But never before have the forces of Ruin amassed in such numbers, and nowhere is safe from despoliation. 

While Horus' rebellion burns across the galaxy, a very different kind of war rages beneath the Imperial Palace. The 'Ten Thousand' Custodian Guard, along with the Sisters of Silence and the Mechanicum forces of Fabricator General Kane, fight to control the nexus points of the ancient eldar webway that lie closest to Terra, infested by daemonic entities after Magnus the Red's intrusion.