As the Emperor marshals his armies to reclaim the galaxy for the glory of mankind, one by one his Space Marine Legions are reunited with their missing primarchs. The XVIII Legion are still waiting to find their true identity, unaware their own lord has been found. In the Taras Division, legionaries face annihilation as they take a last, desperate stand against a monstrous ork invasion. Meanwhile, on Nocturne, Vulkan has raised and trained a new force of warriors. Now it is the time for him to lead his sons into battle. Now it is the time for him to truly don the mantle of primarch, not only to save one half of his Legion, but forge a new, indivisible whole.