Iron Gold is a 2018 science fiction novel by American author Pierce Brown; it is the first of a tetralogy which continues the story of his Red Rising trilogy (2014–2016).

Iron Gold takes place ten years after the events of Morning Star (2016), with Darrow "The Reaper" of Lykos and Virginia "Mustang" au Augustus leading the new Solar Republic.

Living as a vigilante in the Asteroid Belt, Lysander (with his mentor Cassius and their pilot Pytha) rescues Seraphina from an Ascomanni attack on her ship.

At her mother Dido's command, Seraphina has retrieved footage of Darrow and Victra's destruction of Ganymede's dockyards.

Pursued by Ascomanni, Lysander follows Seraphina's coordinates, allowing her father Romulus' forces to rescue them to Io.

House Raa swears revenge on Cassius for Revus and Thesalia's deaths, though Diomedes recuses.

Intending to co-rule with Romulus, Dido puts him on trial regarding Ganymede's dockyards; he pleads guilty to negligence.

The Syndicate's Duke of Hands recruits Ephraim to kidnap Darrow's son, Pax, and Sevro's daughter, Electra.

Ephraim befriends Lyria and secretly plants a device that disables Kavax's ship on her.

Virginia stops Niobe, Daxo, Theodora, and Holiday from torturing Lyria, who helps identify Ephraim.

The Howlers infiltrate Venus; Apollonius retakes House Valii-Rath from Tharsus, gaining 900 soldiers.

Magnus reveals Atalantia's leadership of his forces, her imminent attack on Mercury, and Pax and Electra's kidnapping.

[1] He later noted, "I didn't think I would write more but I started seeing so many plots, particularly with the Ash Lord and the chaos that happens when an empire falls.

Darrow and Mustang will learn it was easier to throw proverbial Molotov cocktails than it is to govern ten billion souls.

"[2] Besides introducing new characters, the new trilogy will explore planets and elements only briefly touched on in the previous series.

[1] Brown called the scope of the new trilogy "huge" and "far more ambitious than Red Rising", noting: "It spans the solar system, weaves in disparate cultures and moons and planets—most of which had to be created from scratch.

"[3] Comparing the new trilogy to the previous, Brown said, "It has the firefights and midnight duels and blood feuds, but many of the characters are not wrecking balls like Darrow.

"[3] He explained that the novel's title "refers to the original Gold conquerors; the founders of Society who were infinitely tougher, smarter, and more brutal than their descendants would become after 700 years of rule.