Magnus the Red, a mysterious occult ruler, studied the ancient art of warlockry for a long time. Now, as a psайкер—one who can be matched by only the Emperor—he commands his faithful legion of the Thousand Sons on the Great Crusade, searching along the way for lost knowledge in the ruins of dead human civilizations. Fighting alongside his brother Perturabo of the Iron Warriors, Magnus senses an approaching fork in fate: will the Cyclops continue to fight for shared goals, or will it direct its efforts toward further understanding of the Warp?