A great darkness has befallen the galaxy, and the armies of Chaos are rampant. To survive, humanity must retaliate and take back what they have lost. By the will of the reborn primarch, Roboute Guilliman, is the Indomitus Crusade launched – a military undertaking that eclipses all others in known history. From the Throneworld of Terra does the Avenging Son hurl his fleets, their mission the very salvation of mankind.