It is the 41st Millennium. For more than a hundred centuries The Emperor has sat immobile on the Golden Throne of Earth. He is the Master of Mankind by the will of the gods, and master of a million worlds by the might of his inexhaustible armies. He is a rotting carcass writhing invisibly with power from the Dark Age of Technology. He is the Carrion Lord of the Imperium for whom a thousand souls are sacrificed every day, so that he may never truly die.

Yet even in his deathless state, the Emperor continues his eternal vigilance. Mighty battlefleets cross the daemon-infested miasma of the Warp, the only route between distant stars, their way lit by the Astronomican, the psychic manifestation of the Emperor's will. Vast armies give battle in his name on uncounted worlds. Greatest amongst his soldiers are the Adeptus Astartes, the Space Marines, bio-engineered super-warriors. Their comrades in arms are legion: the Imperial Guard and countless planetary defence forces, the ever vigilant Inquisition and the tech-priests of the Adeptus Mechanicus to name only a few. But for all their multitudes, they are barely enough to hold off the ever-present threat from aliens, heretics, mutants - and worse.

To be a man in such times is to be one amongst untold billions. It is to live in the cruelest and most bloody regime imaginable. These are the tales of those times. Forget the power of technology and science, for so much has been forgotten, never to be re-learned. Forget the promise of progress and understanding, for in the grim dark future there is only war. There is no peace amongst the stars, only an eternity of carnage and slaughter, and the laughter of thirsting gods.

Prologue: The Fires of Heresy

Arthan Prime, once a prosperous hive world, burned as it floated in the void. Once, it had been the home of over thirty billion Imperial citizens and the source of labor for the nearby forge world of Arthan Gamma, which supplied dozens of Imperial Guard regiments in turn. Covered in vast manmade spires of adamantium, it had been the crown jewel of the Arthan subsector.

Now it was lost. Its populace had been turned from the Emperor's light through the machinations of Chaos, and the subsector had burned in the flames of rebellion. When the planetary defense troopers and local Guard regiments had proven insufficient, the mighty Space Marines had answered the call and delivered the Emperor's Justice to the heretics through bolter and chainsword, and when those had proven insufficient for the task and the world decided lost, Exterminatus. Now, as Arthan Prime twisted and writhed in its death throes, the Space Marines of the Iron Sentinels chapter hunted for the instigator of the revolt, a Thousand Sons sorcerer known to the Imperium as Azar.

Yet the tides of fate are fickle indeed…

Brother-Captain Nemros stared at the dying world far beneath his feet through the command deck of the battle-barge Duty's Shadow. It was, he thought, the least he could do. To dismiss the weight of one's actions was to risk damnation, and so he watched as the former hive world began to slowly collapse inwards, being torn apart by the rampant seismic activities unleashed by the Shadow's cyclonic torpedoes.

It was by his hand that Arthan Prime burned. It had been he who had sent word to the Chapter Master recommending the destruction of the once-loyal planet once it became clear to him that his company was incapable of securing it for the Imperium again, and it had been he who passed on the order to the gunnery crews when the Chapter Master ordered him to prevent the further spread of Chaos through fiery destruction. Even now though, the vile traitor that had orchestrated all of this remained at large.

The purgation of Arthan Prime had been no victory, and the continued survival of Azar the Calculating was ash upon Nemros' tongue. He would know no rest until the heretic had been brought to justice at the tip of his power sword.

The slow pounding of ceramite-clad feet against the command deck, accompanied by the rhythmic tapping of a force staff, alerted him to the approach of one of his brothers, though he remained staring at the world he had killed.

"Brother-Captain," came the dry tone of the Epistolary behind him.

"Vargus," he replied, turning to face the blue-clad Librarian. "Have you had any more luck in your search?"

"No, unfortunately. The foul heretic twists the Warp about him masterfully, using it as a shroud to hide himself from me. It will still be some time before I will be able to begin unravelling the ever-changing threads of the Immaterium that shelter him."

"Hmm," Nemros rumbled. This was unacceptable. The mighty auspex utilized by the Shadow's machine spirit as the ship's eyes had been unable to locate the traitor ship within the debris field that encircled Arthan Prime, meaning that Vargus' mastery of the Warp had been his only other option for finding their foe, a sorcerer of the Thousand Sons traitor legion.

"How fares Sergeant Herox?" he asked. The assault marine squad leader had lost a hand to a heretic wielding a stolen bolt pistol during the initial landing, and had been confined to the Apothecarium since while the apothecaries replaced the missing appendage with a bionic.

"Eager to be up and dispensing the Emperor's Justice once more," Vargus said in a tone that suggested that he had expected no less from an assault marine sergeant.

With a chuckle and a small movement of his power armor-clad hand, Nemros dismissed Vargus and turned back towards the command deck's viewport. Despite the traitor's cowardice and success up until now, he was confident in the Shadow's crew and their ability to intercept any attempt to move to the planet's Mandeville point. One less blasphemous soul would trouble humanity by the end of this day.

Azar, known to his brothers in the fifteenth legion as Azar the Calculating, stared at the loyalist battle-barge as it hung in orbit over his greatest triumph yet. Beneath a leering mask of Warp-touched ceramite, scarred and mutated lips twisted into a hidden smirk.

Tzeentch was smiling upon him, the fickle attention of the God of Lies focused solely upon him in this moment as he stood aboard the bridge of the Unspeakable Knowledge. It was a satisfying reward for all of the unseen effort he had put into corrupting the corpse-worshipping fools, and he reveled in the attentions of the Neverborn that sang his praises throughout the Warp. After naught but a few whispered promises, the bloated nobility of Arthan Prime had willingly given themselves over to his patron deity in the hopes of achieving even more power over their subjects. Eventually they had succeeded in opening a rift into the Warp out of which millions of daemons had poured through and the cultists were ripped to shreds by the very creatures they had hoped to master, their souls devoured by the animalistic daemons.

PDF troopers and Imperial Guard soldiers had moved to halt the flow of the monstrosities invading their homeworld, but had been confounded by conflicting orders from their superiors. When two regiments had been lured into a trap and either destroyed or driven to madness by the Tzeentchian daemons that they had sought to oppose, the entire Imperial command structure had been purged due to suspected heresy, the executioners completely unaware that those they were killing were, in fact, innocent.

Any hopes of a swift outside response had been shattered when the astropaths assigned to the planet twisted and changed into writhing masses of flesh and bone inside their tower. The last chance that Arthan had, that of the local Imperial Navy ships sending for help, was lost when the maddened sailors turned the mighty weapons of their vessels against each other and themselves, destroying the fleet in a series of explosions and detonated Warp drives.

The arrival of the loyalist lapdogs had been unexpected, but Azar had long since learned to plan for the unexpected. One did not survive long in the service to the Changer of the Ways otherwise. Swiftly retrieving what he had come for, he and his Rubric brothers had returned to their cruiser just as the Space Marines had bathed Arthan in fire. Ever since, Tzeentch's blessing had hidden him from the sight of the loyalists.

All that stood between him and further favor from Tzeentch was a lone battle-barge. The unseen smirk grew larger. Days of preparation had led him to this moment. Now was the time to teach these fools just what it meant to go against the powers of Chaos.

Casting his mind out of his body and into the depths of the Warp, he awoke the Neverborn that were bound to the hull of the Knowledge and sent a psychic pulse to the daemons possessing the ship's weaponry. It was time to end this farce.

The first warning Nemros had was a shudder that rocked the Shadow, causing him to stumble and sending a few of the crew flying out of their seats. Behind him, he could hear the battle-barge's shipmaster shouting orders to bring the ship into a combat state. In front of him, he could see the traitor ship emerging out of nowhere with its weaponry blazing, the first shots of which had bypassed the Shadow's void shields and impacted on the adamantium hull, leaving behind a daemonic flame that ate away at the blessed metal.

"Brothers," he snarled into the vox installed within his blessed helmet, "The traitor shows himself at last! In the name of the Emperor and the Primarch, our retribution will be swift!"

His vox roared in response, his brothers shouting oaths of vengeance and prayers to the Emperor as the Shadow shuddered once more, this time as a spread of torpedoes launched from their tubes and sped towards the Chaos vessel while venerable plasma projectors fired spears of superheated gases that shot through the void to splash upon Chaos-touched void shields.

Beneath his helmet, Nemros smiled wickedly knowing that, sorcery or not, the Imperial citizens of Arthan Prime would soon be avenged.

Suddenly a massive Warp rift blossomed in front of the Chaos vessel, despite the traitor ship being nowhere near the system's Mandeville point. It was commonly considered impossible amongst Imperial Navigators to open a rift so close to a planet. Nemros was unsure as to why, the vagaries of the Warp were lost upon him, but he was certain that allowing the sorcerer to complete whatever ritual he had begun would have dire consequences for the Space Marines and crew of the Shadow.

A volley of macro-cannon fire rocked the ship as he made to turn towards the Shadow's shipmaster and roar at the man to destroy the traitor vessel now when something caught his enhanced eye. Before he could even blink, let alone process the sight, the energies of the Warp right shot outwards, engulfing both the heretic vessel and the Shadow.

Before Azar rested the ancient device that he had recovered from the deepest and most heavily sealed vault within the depths of Arthan Prime's crust. Forbidden manuscripts recovered centuries earlier that had led him here had placed the time of its construction during some time in the Dark Age of Technology, hinting at what was possibly humanity's first attempt to master the shifting tides of the Warp.

Azar, however, was uninterested in whatever history this machine had. All of his focus and his psychic might was invested in the ritual that used the device as a catalyst to channel the energies of the Warp. His studies and dreams had shown him that upon successful completion, he would be instantaneously teleported to anywhere in the galaxy that he so desired, while the resulting backlash would consume all those near the Warp rift, casting them into the Warp for all eternity.

The sorcerer ignored the shudders of the Unspeakable Knowledge as the mighty Neverborn he had bound to it took control of it to fight the loyalist battle-barge. He ignored the weapon fire that splashed against the void shields, confident that they would hold long enough for the ritual to be completed. All that he was, was focused upon the ritual, for even the tiniest lapse in attention would have catastrophic results.

So it was that he was caught off guard for a fraction of a second when the distant laughter of Tzeentch echoed through his mind at the same moment that the loyalist fire overwhelmed the void shields that the Neverborn had been neglecting in their eagerness to fight, allowing massive shells to smash into the ship's hull.

"No!" he screamed in rage as the energies that had sustained the ritual were ripped from his control and blasted outwards in a nova of indescribable colors and madness made manifest.

As the Unspeakable Knowledge was blasted into the Empyrean, all Azar could hear was the shrieking of the predators of the Sea of Souls, and the ever-changing laughter of his patron deity.