In surviving the horrors onboard the Eisenstein, Nathaniel Garro proved his courage and absolute loyalty to the Emperor. On his return to Terra, Garro is despatched on a mission of even greater importance - a mission given to him by Malcador the Sigillite himself.

He soon finds himself back amongst the stars and on the fields of battle, thrust into a warzone where the Ultramarines are purported to be battling a greenskin invasion. Once again Garro must fight for survival, but now he also fights to achieve a higher purpose....