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.

On an Imperial outpost world on the fringes of tau space, the renowned Commissar Ciaphas Cain and his fractious regiment of Valhallan Guard, newly created from the remnants of two devastated units, find themselves in the middle of a war. As the Astra Militarum struggle to contain worldwide civil insurrection, can the wily Commissar Cain identify the real villain before the planet is lost to the Imperium forever?

Under almost constant besiegement by the hosts pouring from the Eye of Terror, Cadia acts as a bulwark against tyranny and death. Its fortresses and armies have held back the hordes of Chaos for centuries, but that grim defiance is about to reach its end. As Abaddon's Thirteenth Black Crusade batters Cadia's defences, and armies of the Imperium flock to reinforce this crucial world, a terrible ritual long in the making comes to fruition and the delicate balance of this brutal war shifts.

Fell times have come to the galaxy. Cadia has fallen, destroyed by the onslaught of Chaos. A Great Rift in the warp has opened, and from its depths spew daemons and the horrors of Old Night. But all hope is not lost… A hero, long absent, has returned, and with him comes the wrath of the Ultramarines reborn. Roboute Guilliman has arisen to lead the Imperium out of darkness on a crusade the likes of which has not been seen since the fabled days of the Emperor. But never before have the forces of Ruin amassed in such numbers, and nowhere is safe from despoliation. 

Constantin Valdor. It is a name that brings forth images of heroism, honour and peerless duty. For it is he who commands the will of the Legio Custodes that most esteemed and dedicated cadre of elite warriors. He is the Emperor’s sword, His shield, His banner and he knows no equal. Clad in shining auramite, his fist clenched around the haft of his Guardian Spear, he is the bulwark against all enemies of the throne, within or without. Nearing the end of the wars of Unity, Valdor’s courage and purpose is put to the test as never before.