It is the 31st millennium. The forces of humanity have reached the stars. Under the benevolent leadership of the Immortal Emperor and his superhuman sons, the primarchs, the Imperium of Man has stretched out across the galaxy. It is a golden age of discovery and conquest. But now, on the eve of victory, the Emperor leaves the front lines, entrusting the great crusade to his favourite son, Horus. Promoted to Warmaster, can the idealistic Horus carry the Emperor's grand plan? Worse still, this promotion has sown discontent amongst his brothers. How long before this escalates into all-out mutiny?