A monstrous mechanical planet destroys all life in its path, and the Imperial Navy is unable to stop it. Then the Space Marines of the Adeptus Astartes Chapter take a decisive step. They break through the protective screen and land on the surface of the mysterious sphere. In continuous battles, the Astral Knights move forward, at the cost of their lives, obtaining grains of knowledge about the ominous world, in the hope of revealing its secrets and stopping the enemy before their strength runs out.