The fleet of the Warmaster’s 63rd Expeditionary Force have departed the shattered system of the interex en route to Davin at the behest of First Chaplain Erebus of the Word Bearers Legion. Expecting to find a world left under control and compliance of the Imperium of Mankind, the newly christened Sons of Horus Legion instead finds treason. The occupational forces left behind by the Warmaster Horus himself have turned against the Emperor and the ideals of the Imperium’s Great Crusade, and Horus vows revenge against those he once trusted who have betrayed him.

The fictional universe represented by Warhammer 40,000 is intricate and full of no small amount of intrigue. There are hundreds of factions at work and in motion, set against one another. Plans within plans, mechanizations and motivations that prop up the grim darkness of the war without end in the 41st Century of the Imperium of Mankind. Within the pages of the Horus Heresy, a trilogy-in-progress, what can be described as the single most important chain of events in the history of humanity are brought to light and out into the open in colored detail rather than objective narration from the Imperial point of view; the civil war that befell the Imperium after the spiritual corruption of the Warmaster Horus, mightiest of the Primarchs.