The Inquisition (Dan Abnett)

Dan Abnett's novels of the Inquisition - the secretive order that hunts heretics, aliens and daemons across the Imperium of Man in the Warhammer 40,000 universe - told across three linked series. Gregor Eisenhorn's long career, and his slow drift from orthodoxy towards the powers he was sworn to destroy, comes first. His former pupil Gideon Ravenor carries the story on in a trilogy of his own. The Bequin books then bring the two men into open conflict, seen through the eyes of Alizebeth Bequin, a young woman caught between them. The third Bequin novel, Pandaemonium, has yet to be published.