The first thing you need to know about The Unremembered Empire is that it is not really a story so much as a space where lots of unresolved plot threads come together and then are spun off in new directions. In broad terms, Unremembered Empire chronicles the beginning of the Imperium Secundus, a kind of backup Imperium created by Roboute Guilliman who, cut off from the rest of the galaxy by the Ruinstorm, believes that Terra has fallen and the Emperor is dead. Central to this undertaking is the Pharos, a xenos beacon on the planet Sotha that is able to pierce the warp storms and draw scattered loyalists to Macragge. This is where the first of our unresolved plot threads pops up, with loyalist Iron Warrior Warsmith Barabas Dantioch, last seen in The Iron Within, operating the beacon for Guilliman. The activation of the beacon draws in many scattered loyalists, including Alexis Polux and his contingent of Imperial Fists last seen in The Crimson Fist, and, eventually, half of the Dark Angels Legion led by the Lion himself. Guilliman and the Lion form an uneasy alliance, with the Lion more than prepared to annihilate Imperium Secundus if he thinks Guilliman is attempting to usurp the Emperor. However, it is not the Lion but his unwilling passenger who is the biggest threat, as Konrad Curze, trapped in the bowels of the Invincible Reason since Prince of Crows, escapes the ship and makes his way down to Macragge to cause havoc.
The Unremembered Empire is the sequel to many books, including Vulkan Lives. In one of the more bizarre plot threads that the Heresy writers have come up with, Vulkan's teleport at the end of that novel deposits him in the atmosphere above Macragge. His flesh seared away by the heat of re-entry, Vulkan dies again and his corpse crashes into Macragge Civitas. He returns to life in a medical centre but is now completely insane, mind unhinged by the torments he has endured. Other characters from Vulkan Lives arrive on Macragge as well, John Grammaticus sent there by the Cabal to kill Vulkan with the fulgurite and Barthusa Narek following him to steal the weapon for his plot to kill Lorgar. Damon Prytanis, Perpetual assassin last seen in Betrayer, rocks up to ensure John completes his mission, but everything is put on hold when Curze rampages through the Fortress of Hera in a night of blood and death.
The action sequence of Curze marauding through the fortress is the climax of the novel. He almost manages to kill the Lion and Guilliman, but they are saved by Pharos ex machina. A sequence in which he terrorises Guilliman's adoptive mother Euten is clearly inspired by horror movies, but she is saved first by the watch-pack of Space Wolves sent to observe Guilliman and second by insane Vulkan, who breaks out of containment to confront Curze. Their brawl across the rooftops is brutal and visceral, and of course Vulkan dies a few more times. By this point I think Vulkan is just the HH writing team's stress ball, constantly killed and revived for their gratification. Despite all the odds Curze manages to escape, and both he and Vulkan are present for the final scene with Grammaticus, Prytanis and Narek. Vulkan gets killed a few more times, Prytanis deals with Curze by chucking a daemon at him and Grammaticus stabs Vulkan in the heart with the fulgurite, seeming to permanently kill him but in fact sacrificing his immortality so that Vulkan will eventually be resurrected (see Deathfire). Narek, knocked out of the fight by Curze, is caught at the scene and imprisoned by the Ultramarines. Then, just as things are finally winding down, Sanguinius and the Blood Angels arrive and Guilliman and the Lion crown Sanguinius as the new Emperor.
The Unremembered Empire is a fantastic book, even if it stretches credulity at points. Functionally it is like a fist that gathers up a bunch of loose plot threads and clenches them together into a book, something which the Heresy series sorely needed. In terms of entertainment it is engrossing and like all of Dan's work superbly written. For both of these reasons, is it is an absolute must-read for any fans of the Heresy.
