Horus Rising

The first installment in The Horus Heresy series is set in the 31st millennium, during the Great Crusade. For two centuries, the Emperor of Mankind has led armies of genetically engineered supersoldiers, the Space Marines or Astartes, across the galaxy to reunite scattered human civilizations and destroy hostile alien species. The Astartes are organized into Legions, each led by a primarch, a superhuman being created by the Emperor as both general and surrogate son. After a decisive victory on Ullanor, the Emperor has returned to Terra, humanity's homeworld, to pursue undisclosed work, appointing his favored son Horus as Warmaster, supreme commander of all military forces. The novel follows Garviel Loken, a captain of Horus's own Legion, the Luna Wolves, as escalating crises test the foundations of the Imperium, humanity's expanding galactic empire, and plant the seeds of a galaxy-consuming betrayal.

The story opens with Loken recounting "the day Horus slew the Emperor." The 63rd Expedition Fleet has discovered a human civilization that survived the Age of Strife, a millennia-long period of isolation and catastrophe, under its own self-proclaimed Emperor. When this false Emperor murders Horus's envoy, Captain Hastur Sejanus, diplomacy collapses into war. Loken leads Tenth Company into the palace, battling through elite bodyguards called the Invisibles, who wield cloaking technology and devastating energy weapons. Loken discovers the true false Emperor hidden on a golden throne behind an invisibility field. The hidden ruler unleashes a force blast that hurls the Astartes from the tower, but Horus teleports in, fires a single shot, and destroys the impostor.

Three months later, remembrancers, civilians commissioned by the newly formed Council of Terra to document the crusade, arrive aboard the expedition fleet. The military resents the Emperor's withdrawal and the civilian government now overseeing Imperial affairs. Among the remembrancers are Mersadie Oliton, a documentarist who begins an uneasy working relationship with Loken; Euphrati Keeler, a talented imagist; and Ignace Karkasy, a once-celebrated poet whose blunt honesty repeatedly lands him in trouble.

Captain Tarik Torgaddon informs Loken that he has been nominated to join the Mournival, an informal body of four captains serving as Horus's closest advisors, replacing the fallen Sejanus. Loken seeks counsel from Kyril Sindermann, the expedition's Primary Iterator, a secular philosopher who disseminates the Imperial Truth, the state ideology rejecting all religion and superstition. Sindermann argues that Loken's capacity for doubt makes him ideal, comparing him to the ancient "naysmith," a person employed to question and dissent. Loken accepts and is inducted alongside Torgaddon, the brooding Horus Aximand, and First Captain Ezekyle Abaddon. At his first briefing, Loken proposes finishing off remaining insurgents. Horus agrees, but Primarch Rogal Dorn of the Imperial Fists later reveals that Horus orchestrated the moment so the Warmaster could appear as a peacemaker. Dorn tells Loken that Horus needs "an honest voice," someone willing to dissent.

Loken leads the assault on the Whisperheads, a mountain fortress where insurgents have entrenched themselves. Before the drop, a strange voice begins whispering over the vox, the military communications network, identifying itself as "Samus." The fortress falls quickly, but the real horror follows. Sergeant Xavyer Jubal, resentful at being passed over for command, descends into a deep cavern, becomes incoherent, and proclaims himself "Samus." He kills Sergeant Udon and wounds at least two other brothers before Loken fights him in a desperate duel above a chasm, driving his sword through Jubal's chest. The bound corpse later reanimates and transforms into a monstrous creature, its armor shattering as its flesh distends with growths and fangs. The remembrancers have been brought to a nearby township to observe the campaign, and when the creature rampages through the tunnels, it kills two of them before Loken and Nero Vipus, a Tenth Company sergeant, destroy it. Abaddon establishes a cover story attributing all casualties to insurgents.

Horus visits Loken privately and explains that the warp, the immaterial dimension used for interstellar travel, contains entities that can be called "daemons," but insists these are extra-dimensional creatures whose powers merely seem sorcerous. He speculates that the Emperor returned to Terra to master the warp and admits with visible pain that his father did not share the specifics with him. Loken accepts the explanation but remains shaken.

The narrative shifts to the planet designated Murder, where a Blood Angels expedition has been overwhelmed by the megarachnid, insectoid aliens whose armor and weapons are fused with their biology. Lord Commander Eidolon of the Emperor's Children has committed his forces without waiting for reinforcements, resulting in catastrophic losses. Captain Saul Tarvitz, a grounded officer of the Emperor's Children, leads survivors in a desperate fight. Tarvitz destroys white stone "thorn trees" the megarachnid use as feeding stations, inadvertently collapsing the local shield-storm. Horus dispatches a rescue force under Torgaddon, who confronts Eidolon for his recklessness and discovers it was Tarvitz, not Eidolon, who broke the storm. When Primarch Sanguinius of the Blood Angels arrives, a six-month extermination campaign begins.

During the voyage, several subplots deepen the novel's tensions. Keeler has secretly photographed Jubal's transformation, producing images that disprove the cover story. Traumatized, she has found solace in the Lectitio Divinitatus, a banned pamphlet promoting worship of the Emperor as a god, and challenges Loken to consider whether he would break ranks if corruption spread. Loken intervenes to save Karkasy from expulsion, vouching for the poet on the condition that he continue telling the truth. Loken also attends a meeting of the warrior lodge, a secret fraternity within the Legion where warriors of all ranks meet as equals. He finds it benign but warns that a culture of secrecy could hide dangerous things. First Chaplain Erebus of the Word Bearers Legion arrives and ingratiates himself with the Mournival.

Three vessels arrive at Murder belonging to the interex, a sophisticated human civilization that has survived independently since the Age of Strife. The interex reveals that Murder was their prison world for the megarachnid. They have co-existed for millennia with the kinebrach, an advanced alien species integrated into their society. The interex fears the Imperium may be corrupted by what they call "Kaos," the destructive force of the warp. Horus pursues diplomacy over Abaddon's fierce objections, privately revealing that he is haunted by the Emperor's parting words and the mistakes he made during the false-Emperor campaign and on Murder.

The delegation travels to Xenobia Principis, a border world of the interex, for a summit. In the Hall of Devices, a combined museum and armoury, the Imperials learn of the anathame, blades of "sentient metal" that can be attuned to a specific target to become that target's nemesis. The summit reaches an impasse, but Loken has a breakthrough conversation with Mithras Tull, an interex commander who explains Chaos as an existential threat and is astonished to realize the Imperials are ignorant of it. The conversation ends when the Hall of Devices is raided, the kinebrach curator murdered, and weapons stolen. The interex blames the Imperials.

Violence erupts. Loken fights Tull, sparing his life, then battles his way to the Warmaster, who is pinned down under heavy fire. Horus whispers anguished questions to his absent father. When interex forces close in, Horus seizes a fallen brother's weapons and leads a ferocious last stand until Aximand's forces break through. The Imperials extract under fire.

In the aftermath, Horus decrees that the Luna Wolves will henceforth be known as the Sons of Horus. Deep in the bilges of the flagship, Erebus examines the stolen anathame, revealing that he raided the Hall of Devices, murdered the curator, and deliberately sabotaged the summit. The novel closes with Loken telling Mersadie, with absolute conviction in his commander, that the expedition's next stop is a brief detour at Erebus's request: a little moon in the Davin System. The story continues in False Gods.