In the nightmare future of the 41st millennium, Mankind teeters upon the brink of extinction. The galaxy-spanning Imperium of Man is beset on all sides by ravening aliens, and threatened from within by malevolent creatures and heretic rebels. Only the strength of the Immortal Emperor of Terra stands between Humanity and its annihilation. Dedicated to His service are the countless warriors, agents and myriad servants of the Imperium. Foremost amongst them stand the Space Marines, mentally and physically engineered to be the supreme fighting force, the ultimate protectors of Mankind.

Wars rage over airless moons, in the dark, twisted depths of hive worlds and in the cold wastes between stars. From the immaterial realm of warp space, malicious entities send their unspeakable minions to slaughter the Emperor's chosen. Everywhere, soulless spectres and slavering monsters are poised to extinguish the life of Humanity.