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.

Born of the fiery world of Nocturne, the Salamanders believe in self-sacrifice and the sanctity of human life. Their father, Vulkan, was raised on this world, a blacksmith's son from humble origins who became a primarch of the Emperor of Mankind and forged his sons into a Legion. Their saga is one of heroism, betrayal, tragedy and rebirth. They have returned from the edge of extinction more than once, forever embattled, never bowed, the Legion and their primarch the epitome of defiance in the face of adversity. Unto the anvil, born of flame. 

Reborn in body and spirit beneath Mount Deathfire, the primarch Vulkan gathers his most trusted sons and prepares for the final part of his journey. The Legions shattered at Isstvan V have stalled the Warmaster’s advance across the galaxy, but fresh cracks are spreading through the alliance between the Iron Hands, Salamanders and Raven Guard, along with mysterious rumours of the return of Ferrus Manus. Haunted by a sense of destiny unfulfilled, Vulkan must choose between joining their war of vengeance against the traitors and following his own barely understood path all the way to the Throneworld itself.

A galaxy burns and brother turns on brother as the conflict brought about by a beloved son’s betrayal reaches its fateful end. The Warmaster Horus has triumphed. His massive fleet at last nears Terra and the patriarchal Throne of his hated father. Many have fallen to bring this moment about; their tales are the ashes upon which the Heresy was born and prospered. Others have played their own small parts, drops in an ocean of war and blood. None of it matters. Terra looks to the skies as it raises its defences. Armies muster, heroes raise their swords, citizens cower. The war is coming. And nothing can stop it.

Imperium Secundus lies revealed as a heretical folly. Terra has not fallen, though it remains inaccessible. Sanguinius, Guilliman and the Lion El’Johnson, the primarchs of the Triumvirate, must reach Terra at all costs. They seek to defend the Emperor and to atone for their sins. But the Ruinstorm, a galaxy-wide maelstrom of chaos, hides the Throneworld from the primarchs. Now the fleets of three Legions depart Macragge, and the primarchs will stop at nothing to overcome the Ruinstorm.

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? 

Horus’ armada gathers, and he has defeated all enemies sent against him, even the Emperor’s own executioner. One barrier remains before he can strike for Terra and lay waste to the Emperor’s dream. The Beta-Garmon system occupies the most direct and only viable route to the Solar System and Terra. To break it, Horus assembles a war host of incredible proportions and Titans in untold numbers. To lose here is to lose the war, and Horus has no intention of turning back. But the Imperium understands the importance of Beta-Garmon too. 

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. 

As the Warmaster's campaign of galactic domination continues, his generals seek out fresh battlefields to conquer. After leaving the Crone World of Iydris behind, Perturabo strikes for Tallarn. A bitter, vengeful primarch, the lord of the Iron Warriors unleashes a deadly bombardment against the world, killing millions but entrenching the survivors. A brutal, all-consuming armoured conflict ensues, the greatest of the war and one that grinds down all combatants over more than a year of relentless battles.

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. 

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.

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. 

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.

Recalled from the Great Crusade after Ullanor, Rogal Dorn and the VIIth Legion were appointed as the Emperor's praetorians - but only after the Warmaster's treachery was revealed did the full extent of that sacred duty become apparent. Now, the Solar System comes under attack for the first time since the war began, and many of the seemingly impregnable defences wrought by the Imperial Fists prove inadequate. With all eyes fixed firmly upon this new threat beyond the gates of Terra, who in turn will protect Dorn from the enemy within?

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.