Golden Son

More than two years after winning the Institute, Darrow is still living as a Gold infiltrator inside House Augustus, but the next stage of his mission is already failing. At the Academy he loses the final fleet exercise after Karnus au Bellona springs a counter-trap, and hundreds of lowColors die in the battle. Darrow has received no contact from the Sons of Ares since the Institute and had expected to win a fleet he could eventually use for them. Instead, Nero au Augustus treats the defeat and the continuing Bellona blood feud as political liabilities and ends Darrow's service. With the Bellona family waiting for Augustus's protection to lapse, Darrow goes to Luna seeking another way to survive and retain access to power.

On Luna, Darrow accepts an alliance with Adrius au Augustus, the Jackal, despite knowing Adrius killed Pax. The Jackal has built political and economic power through media holdings and criminal networks and wants Darrow as the visible warlord for his ambitions. Darrow also reconnects with Evey, Harmony, and Mickey and learns that Dancer is believed dead and that Harmony's cell has embraced retaliatory terrorism. Harmony shows him unreleased footage proving Eo was pregnant when she was executed, and Darrow temporarily agrees to Ares's plan for him to detonate a radium bomb at the Summit's closing gala. At the gala, however, he decides that mass killing driven by grief and vengeance would not fulfill Eo's purpose. He plants the bomb but refuses to activate it, deciding instead that the Society can be weakened through civil war among the Golds.

Darrow immediately acts on that strategy. He publicly provokes Cassius au Bellona into a duel, reveals that Lorn au Arcos secretly trained him in the razor, defeats Cassius, and severs his sword arm. When Mustang stops Darrow from killing him, the confrontation spills into a wider melee between the Bellona and Augustus factions. During the chaos, the Jackal secretly disables Leto so Karnus can kill him. The Sovereign's forces then attempt to isolate and destroy House Augustus, but Mustang brings Sevro and the Howlers back from the Rim and helps seize Lysander au Lune as a hostage. Darrow uses Lysander to force Aja au Grimmus to release the surviving Augustans from a massacre at their villa. Aja nevertheless attacks Quinn before the escape; Quinn later dies aboard the captured flagship, deepening the fracture between Darrow and Roque and devastating Sevro.

The escape becomes the beginning of open war. Darrow captures one of the Sovereign's flagships, appoints Orion xe Aquarii as its captain, and broadcasts evidence that Octavia violated the Compact. Sevro then forces Darrow to trust him and reveals that Ares sent him after learning Darrow's true identity. A recorded message from Ares says Harmony acted against the Sons' principles, while Dancer appears alive and confirms that Darrow's family is safe. Darrow and Sevro become the first close allies in the book to share Darrow's Red identity openly. Darrow, Mustang, the Jackal, and House Augustus then pursue a strategy based on expanding the conflict: raid Ganymede's shipyards, seize elite Gold students as leverage, and draw other houses into a war that weakens the Society. Darrow also forces the retired Lorn au Arcos into the conflict after Aja and the Bellona move against him, but Lorn kills the surrendered Tactus despite Darrow's promise of safety.

Pliny later betrays Nero and captures much of the Augustan power structure, but Darrow, Mustang, the Telemanuses, the Howlers, Ragnar, Lorn, Roque, Victra, and others retake the fleet. Darrow calls an Iron Rain on Mars before the Ash Lord can arrive. During the campaign he gives Ragnar a Gold razor, releases him from service, and later reveals that Darrow himself was born Red and remade by the Sons of Ares. Ragnar eventually chooses to follow Darrow as a free man rather than as property. Darrow's assault reaches Agea, where he discovers that Fitchner, Sevro's father and the new Rage Knight, is Ares. Fitchner turns on Octavia and rescues Darrow. The resulting coalition wins control of Mars, and Darrow appears closer than ever to turning Gold civil war into the opening the Sons need.

Darrow then tries to repair the personal relationships his strategy has damaged. He and Mustang finally become lovers, while Roque tells Darrow that he has treated friendship as another resource to use. Darrow and Sevro stage a false Sons attack on the Jackal's stronghold to rescue Harmony, Evey, Mickey, and other prisoners without exposing Darrow's allegiance. Fitchner later explains the long-term plan: Nero is expected to adopt Darrow, defeat Octavia, and become Sovereign; Sevro would then assassinate Nero, after which Darrow would try to inherit the Society and dismantle it from the top. Before accepting adoption, Darrow returns to Lykos, sees his mother, and confronts how much his old home and his memory of Eo have changed. He then reveals his true identity to Mustang. Rather than letting Ragnar decide her response by force, Darrow disarms and gives Mustang the choice to kill him. Ragnar also declares his own freedom from Gold rule. The chapter ends before Mustang states what she chooses.

Golden Son closes by reversing Darrow's apparent victory. During his Triumph in Agea, Nero reveals that he has not become a Reformer and intends to betray the Reformers after defeating Octavia, but Darrow accepts Nero's offer of adoption because it fits the Sons' longer strategy. At the private celebration afterward, Roque poisons and paralyzes Darrow. The Jackal's allies and Sovereign-aligned forces attack from within. Antonia critically shoots Victra, Lorn is killed, Cassius returns with the attackers, and Adrius reveals that he arranged Claudius au Augustus's death through Karnus before shooting Nero himself. Roque rejects Darrow's claim that they are brothers and presents Fitchner's severed head, proving that Ares is dead. Darrow ends the novel captured and unable to move, with Nero, Lorn, and Fitchner dead, Mustang, Sevro, and Ragnar absent from the massacre, Victra's ultimate condition unresolved by this source, and Darrow believing that the rebellion he built has been shattered.