Written by Ben Counter.

Warmaster Horus emerges from recovery to command the Imperial forces in their assault on the rebel world of Isstvan III. What begins as a swift victory unravels into betrayal as virus bombs rain down and the Space Marines turn against one another. Ben Counter's masterful conclusion to the opening trilogy delivers the pivotal moment that reshapes the entire Horus Heresy saga—a must-read for fans seeking the turning point where the Emperor's greatest champion becomes his greatest threat.