The heresy is revealed during the brutal purging of loyalist Space Marines on Isstvan III . Major Story Arcs and Essential Reads
by Dan Abnett: The seeds of heresy are sown as the Great Crusade reaches its peak. False Gods Warhammer 40k - Horus Heresy - Books 1-54 -comp...
With 54 books, the series is often viewed as a "historical library" rather than a linear narrative. While every book adds flavor, several are considered essential to the overarching plot: The heresy is revealed during the brutal purging
Following the opening act, the series branches into parallel storylines focused on different Legions and fronts. While every book adds flavor, several are considered
Seduced by the Ruinous Powers of Chaos, Horus turned half of his brothers against the Emperor. The resulting civil war lasted nine years, ending with the siege of the Imperial Palace on Terra. The "Books 1-54" cover this entire narrative, from the first whispers of heresy on the planet Sixty-Three-Nineteen to the final, god-shattering duel aboard the Vengeful Spirit .