The Emperor's vision of mankind ascendant lies in tatters. The Great Crusade is naught but a fading memory. The dream of Unity is no more. But with Horus's rebellion spreading to every corner of the Imperium and war engulfing new worlds and systems almost daily, there are some who now ask: were the signs there to be seen all along?

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.

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....

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.

In the aftermath of the Dropsite Massacre at Isstvan V, a battered and bloodied force of Iron Hands, Raven Guard and Salamanders regroups on a seemingly insignificant death world. Fending off attacks from all manner of monstrous creatures, the fractious allies find hope in the form of human refugees fleeing from the growing war and cast adrift upon the tides of the warp.

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.

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.

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....

With the Dark Angels spread across a hundred systems, primarch Lion El'Jonson stands as Lord Protector of Ultramar - though his true motives are known to few indeed, and old rivalries on the home world threaten to tear the Legion in half. But when word comes of the Night Lords' attack on Sotha, the Lion's brutal actions bring Imperium Secundus once again to the brink of civil war.

In the wake of the Dropsite Massacre at Isstvan V, the survivors of the Salamanders Legion searched long and hard for their fallen primarch, but to no avail. Little did they know that while Vulkan might have wished himself dead, he lives still...languishing in a hidden cell for the entertainment of a cruel gaoler, his brother Konrad Curze.

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.

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?

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.

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.

The Heresy came to Calth without warning. In just a few hours of betrayal and bloodshed, the proud warriors of the XIIIth Legion - Guilliman's own Ultramarines - were laid low by the treachery of their erstwhile brothers of the XVIIth. Now, as the planet is scoured by solar flares from the wounded Veridian star, the survivors must take the fight to the remaining Word Bearers and their foul allies, or face damnation in the gloomy arcology shelters beneath the planet's surface.