From the earliest days of the Great Crusade, Sanguinius - the angelic Primarch of the Ninth Legion - was among Horus's closest and most loyal brothers. However, all this time, his Blood Angels were forced to hide a painful secret regarding their true nature. Horus becomes aware of the legion's flaw, and the Warrior hints to his brother that the key to saving the Angels can be found in the ruins of one of the conquered worlds. The sons of Sanguinius rush there without hesitation. And when Horus' betrayal becomes clear, the Blood Angels will be forced to confront not only the army of Chaos, but also their own daemons, bursting onto the plains of Signus Prime...