When word reaches Macragge that Terra still holds out, the idea of Imperium Secundus becomes madness. Encouraged by the news, Sanguinius, Roboute Guilliman and Lion El'Jonson set out on a journey to protect the Emperor and atone for their sins. However, the Ruinous Storm - a storm of Chaos energies that has engulfed the entire Galaxy - hides the Throne World from the primarchs. With the fleets of the three Legions leaving Ultramar, the Primarchs will stop at nothing, driven by the desire to fulfill their duty and save the Galaxy. But an insidious enemy watches their every move and weaves intrigues, targeting the weak points of the Emperor’s prodigal sons.