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.

The Shadow Crusade has begun. While the Ultramarines reel from Kor Phaeron's surprise attack on Calth, Lorgar and the rest of the Word Bearers strike deep into the realm of Ultramar. Their unlikely allies, Angron and the World Eaters, continue to ravage each new system they come across - upon the garrison planet of Armatura, this relentless savagery may finally prove to be their undoing. Worlds will burn, Legions will clash and a primarch will fall.

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.

Perturabo - master of siegecraft and the executioner of Olympia. Long has he lived in the shadow of his more favoured primarch brothers, frustrated by the mundane and ignominious duties which regularly fall to his Legion. When Fulgrim offers him the chance to lead an expedition in search of ancient and destructive xenos weaponry, the Iron Warriors and the Emperor's Children unite and venture deep into the heart of the great star maelstrom that haunts Perturabo's dreams.

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.

Once the brightest star in the Imperium and always first among his primarch brothers, Horus has dragged the Space Marine Legions into the bloodiest conflict that the galaxy has ever seen. While their allies wage war on a thousand different fronts, the XVIth Legion descend upon the Knight world of Molech - home to the ruling House Devine, and a principle stronghold of the Imperial Army.

In the city of Queen Mab, nothing is quite as it seems. Pariah, spy and Inquisitorial agent Alizebeth Bequin is all of these things and yet none of them. An enigma, even to herself, she is caught between Inquisitors Gregor Eisenhorn and Gideon Ravenor, former allies now enemies who are playing a shadow game against a mysterious and deadly foe. Coveted by the archenemy, pursued by the Inquisition, Bequin becomes embroiled in a dark plot of which she knows not her role or purpose.

In the mysterious city of Queen Mab, the forces of light and darkness are locked in a murderous struggle for truth. The dedicated agents of the Holy Inquisition battle with their shadowy counterparts, the infamous Cognitae, to discover the encrypted identity of the enigmatic, all-powerful King in Yellow. Caught at the heart of this struggle is the pariah Alizebeth Bequin. Bequin must withstand an onslaught of angels, daemons, and even the monstrous warriors of the Traitor Legions, to unpick the greatest riddle of her life. 

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.

Created in the Emperor's own image, the primarchs had long thought themselves to be princes of the universe and masters of their own destiny - they led the Space Marine Legions in glorious conquest of the galaxy, and no enemy of the Imperium could stand against them. However, even amongst this legendary brotherhood, the seeds of dissent had been sown long before the treacherous Warmaster Horus declared his grand heresy.

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.

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.

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.

Vulkan lies in state beneath the Fortress of Hera, and yet many of his sons still refuse to believe that he is truly dead. After a seemingly miraculous rescue by the Ultramarines, Artellus Numeon, once captain of the Pyre Guard, urges the other Salamanders on Macragge to leave Imperium Secundus and return their primarch's body to the home world of Nocturne - there to be reborn in the flames of Mount Deathfire.

The galaxy is burning. The Emperor's loyal primarchs prepare to do battle with Warmaster Horus and his turncoat Legions on the black sand of Isstvan. Such dark times herald new and yet more terrible things still to come, and when Astropath Kai Zulane unwittingly learns a secret that threatens to tip the balance of the war, he is forced to flee for his life. Alongside a mysterious band of renegades, he plunges into the deadly underworld of Terra itself, hunted like a criminal by those he once trusted.