Halo: Silentium

Halo: Silentium is the third and final novel in The Forerunner Saga by Greg Bear. It is the sequel to Halo: Primordium. It was released on March 19, 2013, with an audio edition released simultaneously.

Synopsis
In the opening chapter, a Juridical sent under the orders of the Master Juridical meets the AI Harusipis, who is the guardian of the Domain. He demands to read classified information from it pertaining to the Precursors and crimes against the Mantle, but Harusipis refuses him, telling that no one has such authority. The AI only allows him inside when the Juridical tells him he does have authority to delete him, but he is quickly overwhelmed by the sheer amount of knowledge the Domain forces into him. The guardian of the Domain grimly notes that the Domain has refused him, because it is coming alive, and it is not happy.

Meanwhile, a Catalog assembles with the Lifeworkers doing evacuation efforts on Erde-Tyrene's surface. Catalog is here to investigate the Battle of the capital, which resulted in the deaths of the entire Old Council, and demands a testimony from both the Librarian and her husband the IsoDidact, formerly Bornstellar Makes Eternal Lasting. However, a warning of an approaching Flood fleet results in the IsoDidact having to leave to defend the territory, so Catalog is sent off with the Librarian. While he accompanies her, she tells him about the events that led to her to become a Lifeshaper, and her growing split from the original Didact due to their differing opinions about humanity.

Shortly before the Ur-Didact went into exile, he and the Librarian gathered together at their estate on the world of Nomdagro. An associate of Harusipis visits their home and helps guide the Ur-Didact in the Cryptum's preservation process. This is where the signs between the two drifting apart due to humanity become apparent.

After his exile, things continued to deteriorate on the Forerunner political scene. To remain seen as an asset to the Master Builder, the Librarian proposes an expedition to a local galaxy known as Path Kethona to learn about the Flood's origins. Legend dictated that 10 million years ago, ancient Forerunners journeyed to Path Kethona, but actual records detailing this journey vanished. The Old Council approved of this venture and the Builder caste through in their support for profit and political gain. Ten years after the proposal was approved, the ship Audacity was completed and sped towards Path Kethona. The crew consisted of the Librarian, a Builder named Keeper-of-Tools, a Miner named Cleaerence-of-Old-Forests, and two Lifeworkers named Chant-to-Green and Birth-to-Light. The Audacity would arrive at Path Kethona and discover that Precursor anchors and space bridges existed this far out of the Milky Way. Also amongst the artifacts were ancient Forerunner vessels of war.

Elsewhere in the galaxy we are reunited with the Ur-Didact as he emerges from a stasis-bubble on a broken-down Builder hulk drifting in a Burn, the designation for a Flood infected star system. Also on-board was another Promethean named Sharp-by-Striking, another Catalog and a Builder named Maker-of-Moons. We learn Sharp lost favor with Faber and Maker was going to give Catalog testimony against Faber, so all three found themselves on the broken ship as well. Their destination is a Flood infested world called Uthera, an once rebellious Forerunner world. Eventually a Precursor artifact with slithering star roads appeared and threatened to destroy the ship. Maker gives the Ur-Didact her armor and he and Catalog are captured by the vessel.

Back with Audacity, the Librarian and her crew scan the Forerunner vessels and find nothing of true interest except that any records inside would've been destroyed thousands of years ago since they were uploaded in binary. Eventually, the Librarian, Keeper and Chant went down to the planet of Path Kethona and find a civilization of Forerunners essentially de-evolved by choice. They are about as tall as Manipulars and act more like humans than Forerunners. In fact, the plants and animals around them have Forerunner DNA implanted in them. The Librarian sheds her armor and decides to encounter the natives. They poke and prod her in curiosity, are enamored by their differences in reproduction and then finally an old female, Glow-of-Old-Suns, interacts with the Librarian and bites her.

However, this has a practical purpose: the microbes in her mouth act as organic ancillas and allow the Librarian to understand the natives and opens them up their the history of the Forerunners. The Librarian eventually goes to a valley and sees that nature itself has been turned into an organic Domain. It is here that she would learn that it was Warriors who committed the attacks against the Precursors and that the entire population was exiled here and remained on Path Kathona.

Back at Uthera, the Ur-Didact and Catalog have been captured by the Gravemind and the Ur-Didact is driven into madness. The Gravemind then reveals the true nature of the Precursors. They did indeed reject Forerunners for the Mantle and intended for humans to hold it. The Forerunners did not accept this and drove the Precursors from the galaxy and beyond. Some Precursors survived by going dormant, others became powder that could regenerate their old selves in time, but time rendered it defective and it created sickness and disease. The Precursors vowed that all life would suffer and be in perpetual agony, through their new form as the Flood. The Precursors are the Flood.

Back in the Orion complex, Forerunner defenses continue to fall and the Master Builder is revealed to be alive and well. He rescued the Ur-Didact and the Ur-Didact was given power once again. A meeting occurs on Nomdagro between the IsoDidact, Ur-Didact and Librarian that does not go well. Arguments ensue and the Ur-Didact reveals the Gravemind drove him mad and that he would not let humans attain the Mantle. A Precursor artifact arrives and ravages Nomdagro as the Audacity and Mantle's Approach leave towards the Greater Ark.

On the Greater Ark, a lone Halo is there in anticipation for a Flood assault. Offensive Bias stands at the ready, but a power struggle ensues between the IsoDidact and other Forerunner commanders who think the Ur-Didact should leave them. The Master Builder manages to regain control for him and the IsoDidact by revealing how the Ur-Didact is being used as a pawn for the Gravemind by torturing him with a sadistic message about how Faber's family was absorbed by the Flood.

The Flood led by Mendicant Bias arrive and chaos erupts. In that confusion, the Ur-Didact uses a Composer to compose human populations being stored on the Halo and retreats towards Requiem. The Librarian follows behind him, grieving for the loss of her humans. Chakas, now in a Monitor shell and still on the Greater Ark, is tasked with saving the rest of the humans on the Ark and taking them to the Lesser Ark, still hidden from the Ur-Didact and the Flood. The IsoDidact and the remaining Forerunner commanders with Faber in tow go to the Halo and activate it to buy time. It does some damage to the Precursor artifact in tow with the Flood, but it ultimately destroys the Halo and Greater Ark. Faber remains behind and lets the IsoDidact use his personal translocation portal, and thus is killed to allow his rival's escape.

Chakas manages to save the IsoDidact and takes him to the Lesser Ark. When they reach their destination, the IsoDidact designates Chakas as 343 Guilty Spark and assigns him Installation 04, the other Monitors for the Halos were chosen by being trusted, Chakas follows the same line of reasoning.

On Requiem, the Librarian sneaks aboard with the Audacity by trailing behind the Mantle's Approach. Requiem's defenses also viewed her as a friendly and let her in. The Librarian uncovers the Ur-Didact's plans with the Promethean Knights and finds one Promethean left uncomposed, Endurance-of-Will. Endurance, a former love interest of the Ur-Didact, is convinced to help the Librarian take down the Ur-Didact and seal him in a Cryptum. Once done, the Librarian tasks Endurance to watch over the Didact for as long as she can and leaves Requiem for Earth.

The Librarian then draws the Flood towards Earth to allow the IsoDidact to fire the seven Halos produced by the Lesser Ark. During her last days on Earth, the Gravemind sends down ancient human essences, including the Lord of Admirals, to reveal that the Domain was created by the Precursors as the collection of wisdom from over 100 billion years of knowledge and that is was engrained in Precursor architecture for safe keeping. In short, the Domain is the mythical Organon. Sadly, the Librarian realizes that the Halos will destroy all of this, but sincerly hopes humanity will still inherit the Mantle.

At the Lesser Ark, the IsoDidact activates the rings and asks for forgiveness. In the end, 343 Guilty Spark reflects on the Halos working their power throughout the galaxy and forgets his old life.

Epilogue
At the end of the novel, a code to a hidden epilogue is included. It links to a hidden video on Halo Waypoint, which gives a forty minute narration from the perspective of Riser.

Forerunners

 * Birth-to-Light
 * Bitterness-of-the-Vanquished
 * Boundless
 * Carrier-of-Immunity‎
 * Catalog
 * Celebrator-of-Birth‎
 * Chant-to-Green
 * Clearance-of-Old-Forests
 * Dawn-over-Fields
 * Endurance-of-Will
 * Examiner
 * Faber
 * Falchion
 * Glow-of-Old-Suns
 * IsoDidact
 * Keeper-of-Tools
 * Librarian
 * Maker-of-Moons
 * Sharp-by-Striking
 * Tactician
 * Ur-Didact

Artificial intelligences

 * 343 Guilty Spark
 * Haruspis
 * Mendicant Bias
 * Offensive Bias
 * The Warden

Humans

 * Forthencho
 * Riser
 * Vinnevra

Promotion
On February 11, 2013, an announcement was released on Halo Waypoint that in the weeks leading up to the release of Silentium Tor Books and 343 Industries would be sending out encrypted communications via halowaypoint.com bulletins and forums, which will allow fans to unlock additional content. There will also be embedded data in the text of the Halo: Silentium paperback and e-book editions. Players can unlock this content in the Classified menu at Halo Waypoint. The unlocked contents are 20,000 experience points for multiplayer and an audio video called "Rebirth", a story narrated by Greg Bear and acts as an epilogue for Silentium. It tells the story of Riser and his last encounter with the IsoDidact.

Trivia

 * "Silentium" is Latin for "silence", "stillness", "inactivity" or "cessation", which reflects the effect of the Halo Array's galaxy-wide activation on the Forerunner civilization and life in the galaxy.
 * Like the other books, the contents Halo: Silentium are extracted in-universe from a Forerunner artifact. In this case, it is two sources: the carapace of a deceased Catalog (designated Forerunner remains #879) and a damaged Monitor.
 * The preliminary cover art, illustrated by Nicolas "Sparth" Bouvier, depicts a vast Forerunner structure with a Cryptum floating in the center and several ships flying by, while the final cover art depicts the Didact observing a hologram of a Cryptum and his wife, the Librarian; the preliminary cover image remains in the background. The original cover illustration was used to promote the novel without giving spoilers as to the appearance of the Forerunner characters, which was not revealed until Halo 4. The final cover art was done as a collaboration between Sparth and Halo 4 concept artist Gabriel Garza.
 * The novel was originally set to be released on January 8, 2013, but the release was later delayed to March 19, as additional time was required to make the story of the novel fit seamlessly with that of Halo 4.