When his servant Ctesias meets his end, the Thousand Sons arch-sorcerer Ahriman is thrust into a deadly conflict with a creature of darkness, a being from the beginning of time whose cunning and thirst for power are the equal of his own – the first daemon prince of Chaos, the dreaded Be'lakor. As the daemon taunts Ahriman with the very secrets of creation, the sorcerer tries to bargain with the beast for Ctesias’s life... but can a deal with a daemon ever be honoured?