Ctesias, the oldest Space Marine and former prisoner of Amon of the Thousand Sons, recounts an event that played a decisive role in his fate. Following the demise of Amon, Ctesias enters the service of Ahriman, the exiled First Captain of the disintegrating Legion, and finds himself drawn into a tale of Ahriman's machinations involving both the daemons of the Warp and a mysterious dead oracle.