Tearing itself apart from within, the Imperium is still virtually powerless to resist the ork advance. When the Adeptus Mechanicus reveal they have discovered the orks' point of origin, the Adeptus Astartes start to gather their forces for a massive assault on their enemy's home world. But what the Imperial forces need is a figurehead, a hero from legend to lead them - a primarch. Meanwhile, on the planet Caldera, a mighty armoured warrior fights tirelessly against the orks - is he the saviour the Imperium seeks?