The Horusian Wars series in Warhammer 40,000 runs to 3 books. Below is the full reading order in series sequence, so you know exactly where to start Horusian Wars and what to read next.
Original summaries and chronology labels generated from the same catalog powering the atlas.
John French
Inquisitor Covenant hunts a hidden conspiracy through the underbelly of the Imperium, drawing together a band of agents bound by suspicion and necessity. As a radical scheme involving forbidden artefacts comes to light, the line between heresy and salvation grows perilously thin in this opening to the Horusian Wars.
667.M41 - 999.M41
era date, medium confidence
John French
Inquisitor Covenant and his retinue press their dangerous investigation as a Horusian plot to forge a vessel for a fragment of divine power gathers momentum. Rival inquisitors, assassins, and the lure of forbidden knowledge converge, deepening the moral murk of the secret war within the Imperium.
667.M41 - 999.M41
era date, medium confidence
John French
This collection gathers shorter tales from the Horusian Wars, following Inquisitor Covenant and his agents through schemes, betrayals, and confrontations across the shadowed corners of the Imperium. The stories expand the wider conflict between radical and puritan factions of the Inquisition surrounding Covenant's hunt.
667.M41 - 999.M41
era date, medium confidence