Graham McNeill
The Enemy of My Enemy

Within the Eye of Terror the Iron Warriors homeworld has become a living hell for many brave warriors of the Imperium.
Warhammer 40k
short

Also in:
Ultramarines: Quick Reads Collection
Honour And Vengeance: Uriel Ventris Vs Honsou
Ultramarines Xmas Ebundle
Iron Warriors: the Omnibus
Eye of Terror