War is unending in the life of a Space Marine. After defeating tau forces, Captain Uriel Ventris of the Ultramarines has returned to the Chapter's homeworld of Macragge, but there is little respite. The Ultramarines are thrust back into battle, and this time the enemy is the Chapter's greatest nemesis. The traitorous Iron Warriors, led by renegade Warsmith Honsou, have gathered together a massive and brutal warband. Their target is the realm of Ultramar. Their objective is total annihilation. It is a final showdown between legendary Space Marines, and Uriel Ventris must take on the might of Honsou if he is to save his Chapter's homeworld.