In spite of the corruption of Corax's plans to rebuild his Legion after the Dropsite Massacre, the surviving Raven Guard remain defiant. Happening upon a stricken Word Bearers vessel far behind the front lines, they find evidence of a new alliance between the traitors and the forge world of Constanix II. With rumours of terrifying new war machines stalking battlefields across the sector, it is a threat too great to ignore.

Renouncing fealty to all masters or driven mad by the rigours of war, the Blackshields are a stain upon any Legion they once served. Regarded as little better than pirates, their loyalty is only to themselves. Infamous among their mercenary ranks is Endryd Haar, a former World Eater, driven by hatred, his blade pledged to no banner but his own. But estranged from his Legion and surrounded by a battered warband of warriors, how long can Haar and his Blackshields hope to endure?

After the horrors of Istvaan V, Horus declares outright war against the Imperium. In the shadows of the Emperor's Palace, powerful figures convene. Their plan is to send a team of assassins to execute the arch-traitor Horus and end the war for the galaxy of mankind before it's even begun. But what they cannot know is that another assassin is abroad already, with his sights firmly set on killing the Emperor.

After the destruction of Monarchia and the Emperor's reprimanding of the Word Bearers Legion, the primarch Lorgar spent many long years searching the stars for the universal truths of the cosmos - when he finally came to gaze deep into the Eye of Terror, with grim inevitability he found that the Eye stared back.

The Pharos stands as a beacon of light in the darkness, a whisper of hope in the silent void, a bastion of defiance in the face of treachery. Without it there could be no Imperium Secundus - why, then, do the masters of Ultramar know so little about its operation, or the dangers it could present? Young Oberdeii and Tebecai, Scouts of the 199th Company, descend into the depths beneath Mount Pharos in search of the truth...though it may haunt them for all time.