Graham McNeill
Eye of Vengeance

Scout Sergeant Telion, the Ultramarines’ master marksman, leads the defence of the agri-world of Quintarn against a twisted Dark Mechanicum priesthood known only as the Bloodborn.
Warhammer 40k
short

Also in:
Honour And Vengeance: Uriel Ventris Vs Honsou
Ultramarines
Ultramarines
Ultramarines: the Second Omnibus
Ultramarines: Quick Reads Collection