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.

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?

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?

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.

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.

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.

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.

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.

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.

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.

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 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? 

As the darkness of the war slowly consumes the galaxy, those who still serve the Throne are faced with a struggle for their survival and the continued existence of everything they hold dear. With the threat of the Warmaster's fleet looming ever closer to Terra, it will fall to such heroes to halt the tide, but the enemies arrayed against them are powerful, and the burden of loyalty is great....

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.