Lieutenant Xedro Farren is a Primaris Marine, stronger and more adept than even the Space Marines his brotherhood is sent to fight alongside. As the Dark Angels and the Primaris Marines fight a trauma-scarred force of T'au hellbent on destroying their former allies, the true quarry becomes clear – the shadowy instigator of a psychic curse that could plunge a string of Imperial planets into madness. As worlds burn in the fires of battle, an unthinkable pact is struck, with the Primaris Marines peeling back layer after layer of deceit to find the appalling truth. Can Farren hope to emerge from this web of lies without losing his honour – or come to that, his life?