The Inquisition War deals with one such individual in Inquisitor Jaq Draco and his brave companions who help in this endless fight against the ruinous powers. Draco finds himself travelling across the Imperium of Man as he tries to end a conspiracy that threatens everyone with complete enslavement.
Watson is a wonderful writer, and he really brings out the gibbering nature of the followers of Chaos, and the constant threat to humans from them. In fact role players who are playing Dark Heresy could use this wonderful collection to find many ideas for their own campaigns.
I'll let Draco speak for himself:
"What does the name of inquisitor mean? Many people would answer: destroyer of mutants, hammer of heretics, scourge of aliens, with-hunter, torturer. Yet really the answer is: a seeker of truth, however terrible the truth may be. As a member of the Ordo Malleus I am already a secret inquisitor. Yet the truth I must disclose involves the revelation of an even deeper, more sinister secrets than those known to members of our covert order."
A fun read, especially if you know anything about the Warhammer 40,000 universe and setting.