On the prison world of Zartak, darkness has fallen on arbitrators and inmates alike. The Night Lords have come, bringing with them the shadow of fear and pain. But these monsters are not the only ones with an interest in Zartak. From the void, running on silent, another fleet emerges. These Space Marine warriors are grey-clad and white-faced, and their eyes are as black as the Outer Dark – the savage Carcharodon Astra.

Belisarius Cawl, Archmagos Dominus of the Adeptus Mechanicus, is the most brilliant mind alive. For 10,000 years he has furthered the cause of mankind, working under the aegis of the Emperor and Lord Commander Roboute Guilliman to prevent the inexorable march of the alien and the traitor. Many call him heretic, but all must recognise the magnitude of his achievements, for who else but he was entrusted to create a new generation of Space Marines?

The Night Lords were once among the most potent forces of the Imperium, Space Marines who used fear itself as their weapon. Now, cast adrift from the Emperor's light and hunted as heretics after their monstrous betrayal, the Night Lords clad themselves in symbols of death and fight the Long War, bringing pain and terror to all who worship the corpse-god of Terra. A summons from Warmaster Abaddon sends these rebels on a dangerous journey that leads inexorably to a conflict with the Emperor's chosen warriors, the Blood Angels.

On the grim death world of Fenris, the Space Wolves Chapter selects its aspirants from the best and brightest of the young tribesmen. Ragnar of the Thunderfist tribe finds his life changed forever when he is chosen. After being revived from a savage death on the battlefield, Ragnar is recruited into the fearsome Space Wolves Chapter. He is then thrown into a galactic war against the dark forces of Chaos. However, the implanting of the Canis Helix unleashes his primal instincts and Ragnar must fight to control the beast within him.

For Ianthe, war is all too familiar. A former soldier in the Astra Militarum, she now serves Inquisitor Covenant as an agent of the Throne. Her first mission sees her investigating a cult called the Children of Eternity. Falling foul of the local Enforcers, Ianthe soon learns that war in the shadows is seldom straightforward and that the local, angry law-keepers are the least of her troubles.