Eisenhorn

About the Eisenhorn series

The Eisenhorn trilogy follows Gregor Eisenhorn, an Imperial Inquisitor of the Ordo Xenos charged with rooting out heresy, alien threats, and the corrupting influence of Chaos across the Warhammer 40,000 galaxy. Dan Abnett builds the series as science-fantasy detective fiction rather than straight military SF: Eisenhorn is an investigator first, piecing together conspiracies across decades and star systems with a retinue of specialists, and the trilogy's real tension comes from watching a rigidly orthodox servant of the Imperium slide, book by book, toward using the very forbidden knowledge and Chaos-tainted tools he has spent his career destroying, because they are the only things powerful enough to win.

Xenos (2001) introduces Eisenhorn on the trail of a heretical cult and a dangerous alien relic; Malleus (2001) escalates into daemonic possession and a war within the Inquisition's own ranks; Hereticus (2002) forces Eisenhorn to complete his fall, using banned Chaos-derived power to save the Imperium from a threat orthodox methods cannot touch, at the cost of becoming the kind of heretic he once hunted. It's widely regarded as one of Black Library's best and most influential Warhammer 40,000 series, and a common entry point for readers who want the setting's grim-dark texture without a full war-novel's troop movements.

The story continues directly in the Ravenor trilogy, following Eisenhorn's former protege Gideon Ravenor, and the two threads eventually converge in the later Bequin sequence.