It is the 32nd millennium, and the Imperium is at peace. The Traitor Legions of Chaos are but a distant memory, and the many alien races that have long plagued mankind are held in check by the Space Marines. When a mission to exterminate one such xenos breed on the world of Ardamantua draws in more of their forces, the Imperial Fists abandon the walls of Terra for the first time in more than a thousand years.

After seven years of bitter war, the end has come at last for the conflict known infamously as the Horus Heresy. Terra now lies within the Warmaster’s sights, the Throneworld and the seat of his father’s rule. Horus’ desire is nothing less than the death of the Emperor of Mankind and the utter subjugation of the Imperium. He has become the ascendant vessel of Chaos and amassed a terrible army with which to enact his will and vengeance. But the way to the Throne will be hard as the primarch Rogal Dorn, the Praetorian and protector of Terra, marshals the defences.

For a thousand years, the Sabbat Worlds have been lost to the Imperium, claimed by the dread powers of Chaos. Now, a mighty crusade seeks to return the sector to Imperial rule. And at the forefront of that crusade are Colonel-Commissar Ibram Gaunt and the Tanith First and Only - better known as Gaunt’s Ghosts. Trapped in the grinding trench warfare of Fortis Binary, the Ghosts find themselves drawn into a conspiracy to assassinate the crusade’s leader, Warmaster Macaroth.

The Inquisition moves amongst mankind like an avenging shadow, striking down the enemies of humanity with uncompromising ruthlessness. When he finally corners an old foe, Inquisitor Gregor Eisenhorn is drawn into a sinister conspiracy. As events unfold and he gathers allies - and enemies - Eisenhorn faces a vast interstellar cabal and the dark power of daemons, all racing to recover an arcane text of abominable power: an ancient tome known as the Necroteuch.

Legend tells of a foolhardy expedition, led by the radical Magos Telok, that ventured out into the unknown space beyond the Halo Worlds in search of the 'Breath of the Gods' - an arcane device with the power to unmake and reshape the very stars themselves. Thousands of years later, the ambitious Lexell Kotov musters his Adeptus Mechanicus Explorator fleet and sets out to follow in mad old Telok's footsteps.