Far out on the Eastern Fringe, the realm of Ultramar stands alone. Having weathered the Word Bearers' attack on Calth and the subsequent Shadow Crusade against the Five Hundred Worlds, the Ultramarines primarch Roboute Guilliman now draws all loyalist forces to Macragge as he contemplates a new future for mankind. With the arrival of more and more fugitives from the war that has engulfed the rest of the galaxy, all distinction between friend and foe is lost - isolated from Terra by fearsome warp storms, is Guilliman making a bid for power to rival even the renegade Warmaster Horus?

Read it because
Perhaps the greatest secret of the Horus Heresy is revealed, as Roboute Guilliman commits an act that could be considered treachery. At the same time, primarchs converge on Macragge. Guilliman, the Lion, Vulkan and the insane Konrad Curze all in the same place... there are going to be fireworks.

The eBook edition includes integrated illustrations of characters and events from the story, and an afterword that places the story in context within the series.