The Imperium has been brought to the edge of extinction by an ork invasion of unprecedented scale and depth. Piecemeal strikes against the invaders prove ineffective - for every ork fleet destroyed, five more appear. The only solution is to find and kill the orks' warlord - the Great Beast. Surely if its leader is killed, the greenskins' empire will fall apart in agony of infighting and confusion.

Paralysed by the continued ork invasion of Imperial space, the rulers of Terra continue to fight among themselves. Finally losing patience with the High Council, Koorland - the last surviving Imperial Fist - ousts the Lord Commander and seizes control. Elsewhere, the Fists Exemplar are forced by circumstance to fight alongside the Iron Warriors. Where will such an alliance lead - can a Traitor Legion ever be trusted?

The attempt to hunt down and kill the orks' leader has ended in catastrophe. The Imperium is reeling from the loss of so many beloved heroes, and the military forces of mankind have been reduced to tatters. Koorland now knows that brute force is not the answer - but how else can the orks be fought? In a radical move, he creates small, mixed Chapter units of Adeptus Astartes - compact teams that will hit the enemy hard and fast and with deadly accuracy.

The Imperium's situation has never been more grim - an ork attack moon hangs over Terra, and ork armadas ravage human space. To make matters even worse, eldar strike at the heart of the Imperial Palace, forcing humanity's defenders to fight on two fronts at once. Though it seems nothing can stop the orks - neither brute force, science, nor faith - an unlikely alliance in the furthest reaches of space uncovers the first clue how to defeat the greenskins. The Adeptus Astartes now face an almost impossible task....

Despite the Imperium's best attempts to forestall the ork plague that is wreaking havoc in human space, an ork attack moon now hangs over Terra. As its malevolent presence gazes down at the Imperial Palace, terrified citizens run riot in the streets. In a last-ditch attempt to destroy the attack moon, a proletarian crusade is launched. Thousands of ships large and small head to the moon carrying billions of citizens, all eager to take the fight to the enemy.

As the ork menace ravages the galaxy, the Imperium faces its darkest hour. Its fleets are in ruins, its armies devastated - amongst them the noble Imperial Fists - and even a primarch of myth has fallen against the Beast. As brute force fails, Koorland resorts to increasingly desperate tactics against the greenskins. A final hope lies in deploying the controversial Deathwatch and the Sisters of Silence in a deft strike at the heart of the ork empire.

The Imperium's attempts to defeat the ork menace seem doomed to failure; it is only a matter of time before the greenskins triumph, and mankind is wiped from the galaxy. Yet there is some cause for hope - the psychic weakness of the orks has been found, and a few Sisters of Silence survive. Supported by the full might and technology of the Adeptus Mechanicus, the Space Marines head to the orks' home world one final time. This time there will be no retreat, no surrender. They must succeed...or die in the attempt.

After centuries of peace, the Imperium is thrown into panic as human worlds everywhere are menaced by orks. In a relentless tide of slaughter, ork attack moons destroy planet after planet with gravity weapons of unstoppable power. On Terra, the High Lords are paralysed by the scale of the threat and fail to take any effective action. With entire Space Marine Chapters missing or known to have been wiped out, does anyone have the will and the power to rise to the Imperium's defence?

Across the length and breadth of the galaxy, humankind celebrates its salvation and relishes the prospect of a return to peace. But the war against the orks has driven the political bedrock of the Imperium, exposing its rotten core. One man, one powerful man, decides he has the solution and launches a campaign of destruction so terrible that thousands of years later his actions will still be viewed with horror.

It is the 32nd millennium, and the Imperium is at peace. The Traitor Legions of Chaos are but a distant memory, and the many alien races that have long plagued mankind are held in check by the Space Marines. When a mission to exterminate one such xenos breed on the world of Ardamantua draws in more of their forces, the Imperial Fists abandon the walls of Terra for the first time in more than a thousand years.