From out of the shadows of the Silent War, a hero emerges. Clad all in grey, an errant warrior of the Legiones Astartes kneels before the Regent of Terra, and accepts a solemn new duty - Battle-Captain Garro, once commander of the Eisenstein, now Agentia Primus of Malcador the Sigillite. From the desolation of Isstvan to the halls of the Imperial Palace itself, he stands as a paragon of loyalty and protector of the innocent, ever ready to strike back at the traitorous allies of the Warmaster.

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?

After Isstvan, after Deliverance, the Raven Guard still endure. Their primarch Corvus Corax has rallied countless warriors to his banner, striking back at the forces of the Warmaster on every front - from the degenerate hereteks of the Mechanicum to the cruel legionaries of the Sons of Horus, none shall escape his wrath. But although Corax has managed to stall the physical corruption of his own Space Marines, what of their spirit? And what sinister end must await those who dwell forever in the darkness?

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.

Removed from the concerns of the galaxy at large and regarding the Warmaster's unfolding Heresy with cold detachment, he has dedicated his hollow existence to the preservation of all the knowledge once held in the great libraries of Tizca, should mankind ever seek such enlightenment again. But his sons can see the change in their primarch - he is a broken soul whose mind and memories are slipping away into the tumult of the warp.

Driven almost to the brink of self-destruction at Isstvan V, the Iron Hands now seek vengeance for the murder of their primarch Ferrus Manus. Gathering survivors from the Raven Guard and the Salamanders aboard any vessels capable of warp travel, these Shattered Legions wage a new campaign of annihilation against the traitor forces across the galaxy - a campaign masterminded by legendary warleader Shadrak Meduson.

With the noble Emperor Sanguinius ruling from Macragge, Imperium Secundus stands as a lone beacon of hope even as the Warmaster's forces continue to ravage the rest of the galaxy. Roboute Guilliman, still Master of Ultramar, has convinced his brother that Terra has fallen and that the mysterious Mount Pharos on Sotha now holds the key to mankind's future.

For too long had the Vth Legion ranged out beyond the sight of the wider Imperium, remaining ignorant of the Warmaster's rebellion and the war that inevitably followed. Only once their primarch, Jaghatai Khan, had satisfied himself that the path before them was just and true did the White Scars choose a side, taking the fight to the traitors on every front.

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.

While loyalist and traitor forces clash on a thousand battlefields across the galaxy, a very different kind of war is being fought in the shadows - a war of subtlety and subterfuge, unknown to many, but one that surely holds the key to victory for either side. Rogal Dorn and his Legion prepare to defend the Solar System against the armies of Warmaster Horus, even as Malcador the Sigillite charges his many agents and spies with missions of the utmost secrecy. The future of the Imperium is being shaped by unseen hands....

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.

Of all the Legiones Astartes, the White Scars of Jaghatai Khan remain the most enigmatic and elusive. Born of a civilisation that prizes honour, speed and fearsome loyalty, their allegiance has yet remained unclear even as the galaxy is torn apart by Horus's treachery, and both sides have apparently counted them among their potential allies in the war to come.

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? 

Far out on the Eastern Fringe, the realm of Ultramar stands alone. Having weathered the Word Bearers' attack on Calth and the subsequent Shadow Crusade against the Five Hundred Worlds, the Ultramarines primarch Roboute Guilliman now draws all loyalist forces to Macragge as he contemplates a new future for mankind.

The galaxy burns at Horus' command, and a billion more lives are lost with each passing moment - though it was not always so. Once, the title of Warmaster stood for honour, loyalty and a fierce pride in the strength of the Space Marine Legions. But perhaps by following the myriad lines of destiny and defiance that were already woven around the primarchs and their sons, we may yet come to understand the bitterness that can eat away at even the most steadfast of souls....