

Cibola Burn is the fourth novel in The Expanse series. It was released on June 17, 2014.

The gates have opened the way to a thousand new worlds and the rush to colonize has begun. Settlers are looking for a new life stream out from humanity's home planets. Ilus, the first human colony on this vast new frontier, is being born in blood and fire.

Independent settlers stand against the overwhelming power of a corporate colony ship with only their determination, courage, and the skills learned in the long wars of home. Innocent scientists are slaughtered as they try to survey a new and alien world. The struggle on Ilus threatens to spread all the way back to Earth.

James Holden and the crew of his one small ship are sent to make peace in the midst of war and sense in the midst of chaos. But the more he looks at it, the more Holden thinks the mission was meant to fail.

And the whispers of a dead man remind him that the great galactic civilization that once stood on this land is gone. And that something killed it.

The gates have opened the way to thousands of habitable planets, and the land rush has begun. Settlers stream out from humanity's home planets in a vast, poorly controlled flood, landing on a new world. Among them, the Rocinante, haunted by the vast, posthuman network of the protomolecule as they investigate what destroyed the great intergalactic society that built the gates and the protomolecule.

But Holden and his crew must also contend with the growing tensions between the settlers and the company which owns the official claim to the planet. Both sides will stop at nothing to defend what's theirs, but soon a terrible disease strikes and only Holden – with help from the ghostly Detective Miller – can find the cure.

Colony ships have been going through the wormhole gates and colonizing the worlds within, expanding humanity's frontiers beyond the Sol system at a furious pace. Basia Merton, who previously lived on Ganymede until his son, Katoa, was used in the protomolecule experiment, was one of the first colonists on Ilus, christened “New Terra” by the United Nations. They created a colony on First Landing where the lithium reserves were closest to the planet's surface. Basia builds some makeshift IEDs and destroys the landing pad built so the massive Royal Charter Energy (RCE) colony ship, the Edward Israel, could land and begin their mining operation; however, a shuttle from the ship arrives much sooner than expected, and is downed in the explosion.

Elvi Okoye, an exozoologist, is injured in the shuttle crash, but she survives; many of her crewmates, including the Governor, are killed. Fayez Sarkis, geohydraulics, survives and pairs up with Elvi. Dimitri Havelock, Miller's old partner, works on the security force aboard the Edward Israel.

The Rocinante has been taking jobs escorting ships through the Sol Ring to Medina Station, formerly the Nauvoo and the Behemoth. After they dock, Fred Johnson, leader of the OPA, tells Holden that he's received a video from Chrisjen Avasarala; she wants him to mediate the situation on New Terra, since he's mostly impartial to the UN and the OPA. The OPA has fundamental disagreements with the UN being in charge of handing out contracts for thousands of worlds, so Fred and Avasarala are back-channeling things to keep it from getting out of control. Holden ultimately agrees to take the job, partly because they'll be setting the template for everything that follows, and partly because the money is really good.

The Roci heads through the Ring, but it will still take 73 days to get to New Terra. In the meantime, Holden gets continual demands from both sides demanding that he force the other to concede; the captain of the Barbapiccola insists that they be able to sell their ore, while the captain of the Edward Israel continues their blockade, insisting the independents are selling the lithium illegally. Holden thinks his mission is intended to fail, that both sides are using him as a scapegoat.

Miller continues to appear. Holden asks Miller how he manages to follow him around, and Miller tells him the protomolecule put a local node on his ship during the Ganymede incident, when the monster was in the cargo bay.

Basia's daughter, Felcia, wants to leave Ilus to attend University; she befriends Elvi and asks her to write a letter of recommendation. After a sandstorm, Elvi sees a light in the ruins and investigates; she discovers explosives and reports her findings to the RCE security force.

Coop, the leader of the OPA resistance, tells Basia that the RCE found the explosives and they need to go set them off or they'll be traced back to them. This is just a ruse to get Basia to come along, however. They all show up with weapons and have a shoot-out, killing all the RCE security there.

Chief Adolphus Murtry, head of RCE security on the Edward Israel, takes a light shuttle down to extract the lone surviving security personnel and to stop the insurgents, leaving Havelock in charge of security on the ship.

Holden and Amos land on the planet to absolutely no fanfare; Alex and Naomi, who can't withstand the gravity due to her Belter physiology, head back into orbit. They walk to the town square, where the two opposing sides, headed by the major/coordinator Carol Chiwewe and Murtry, are facing off in a shouting match. Both sides ask Holden to take their side, but he wants to be impartial. Coop threatens Murtry, who in turn shoots Coop right in the eye; he's declared Martial Law on the town. Holden tells Murtry he fully intends to prosecute him for murder, later; Amos tells Holden he knows Murtry gets off on killing, and that he'll probably have to shoot him before long.

At a meeting with other insurgents, Basia convinces them that they need Holden on their side, and that if they escalate things, it will make matters much worse. The group recommends he talk to Holden, since Holden found his son on Ganymede.

Elvi meets with Holden and is a bit smitten by him. She tells him that while humans have evolved for longer than the life on this planet, eventually something here will learn to exploit them, not like a virus, which evolved with humans, but it will learn to "mine" them unless they can build antibodies to fight them off. It's already a problem, however, because they didn't set up a bio-sphere when they landed. Holden tells her they'll get to that as soon as the other crisis is resolved.

Holden holds the first joint meeting between Murtry and Chiwewe in an effort to establish the laws on Ilus. They come to a compromise where the OPA can send ore up to the Barbapiccola, but they have to sign out the mining explosives from the RCE.

While out walking, Miller appears to Holden and explains that the previous inhabitants of Ilus were powerful enough that they remodeled the whole planet, and had an orbital defense system that could've vaporized Ceres, but they were still extinguished by the protomolecule's parent race's killers. Holden runs into Basia on his way back; Basia tells Holden who he is, and tells him they can't make him leave. Holden can tell from his nervous demeanor that he's either in the resistance or knows who is. Naomi calls and warns him that there are massive energy spikes coming from his location.

Havelock reports to Murtry that he's converted their light shuttle into a makeshift fusion bomb, flyable only by him or Murtry. Murtry also wants Havelock to train the scientists to form a militia. Later, Captain Marwick tells Havelock that what happens on the ground could have major consequences for him and his ship when they go back through the Ring with the OPA on the other side.

The Roci picks up something large moving on the surface during the energy spikes; Holden, Elvi, Fayez, and Wei hop in a cart and check it out. They find a large, insect-like being that Holden recognizes as one of the security drones from the Ring Station that was so adept at killing things. It is consuming the grasses and fungus on the ground to repair itself. Holden says they need to retreat as soon as possible, but Wei opens fire on it, and kills it; they burn it to make sure it doesn't resurrect.

Basia goes to another OPA meeting. their new plan is to take out all of the security forces and Holden, in an effort to make it economically inviable to occupy them. Basia doesn't want any part of it and leaves. At home, he tells his wife he's going to talk to Holden about it; she tells him that their daughter is leaving on a shuttle now to go to University and he runs to stop her. When he gets to the shuttle, he realizes she'll be much happier and safer if she goes, so he simply gives her a proper goodbye. He tracks down Holden and warns him about what's going to happen; Holden isn't all that surprised, but says it's irrelevant because they're all leaving the planet anyway, in lieu of the waking alien technology.

Holden gets Murtry and Chiwewe together and tells them they're all leaving, but neither agrees to his plan. Holden ultimately has to threaten to shoot Murtry, but Murtry gets a call from his team, revealing that they all knew about the uprising because he's bugged the entire town, and he already has his people in position. He orders his strike team to attack; they kill everyone inside a nearby house that Murtry dubbed a "terrorist cell". Murtry orders Basia be taken as a prisoner for conspiring with the terrorist, but Holden declares custody of him on behalf of the UN, saying he will be kept as a prisoner on the Roci.

In addition to the energy spikes, there have been twenty heat upwellings on the planet.

The Roci lands and picks up Basia. Naomi gives him free reign of the ship; she doesn't see him as a prisoner since he saved the captain's life. She and Alex have noticed that the RCE has turned its second shuttle into a bomb. They could shoot it with a gauss round, but Naomi opts for the non-violent route and EVAs over to attach a remote cut-off on the engine.

While doing EVA training exercises, someone on Havelock's squad notices Naomi welding on the shuttle. They thrust over to her and she flees, but they use their grapnels to ensnare her; they throw her in the brig.

Holden gets a visit from Miller; Miller admits that the protomolecule has been activating the alien robots on the surface, but also that there's a big empty spot in the global network and he needs Holden to check it out; it may be a remnant of the thing that killed the Investigator's creators. Holden says he'll check it out as soon as they free Naomi.

Up in the sky, one of the moons melts. Elvi goes to warn Holden about it, and also tells him that she thinks they've only encountered the alien organisms on the planet so far that are trying to wake up from hibernation and failing, but it's usually only a small percentage of organisms that fail when awaking, and there are probably plenty more that won't fail.

While in the field, Elvi analyses a butterfly-like animal; it turns out that it's not an animal at all, but another sort of alien machine. Basia's wife, Lucia, the town doctor, asks Elvi to stop by. In her office, she has a boy whose eye has turned green; she thinks it's possibly the organisms that live in the clouds, feeding off the moisture. She tells Lucia she'll talk to her people and Holden, and hopefully they can find a cure.

Over the center of Ilus' largest island, on the opposite side of the planet from First Landing, an enormous eruption occurs, creating tidal waves hundreds of feet high, flattening half the planet, and lighting up the dark side of the planet like a second sun has appeared. The shockwave will soon spread to the other side of the planet. Alex calls Holden and warns him that he's got about 6 hours before the shockwaves hit, which is too soon to bring the Roci down for evacuation or for them to take the RCE shuttle off the planet. They decide the best course of action is to get everyone into the alien ruins.

The storm front hits for 16 long hours. Afterwards, there's nothing left outside but mud, no remnants showing that humans were ever even there. Slimy slugs begin emerging from the ground; someone touches one and immediately dies. Everyone chips in to block all the access points of the ruins from the invasion of the toxic slugs, hanging sheets of plastic on the windows, digging trenches, etc.

Holden tells Murtry they need to get everyone off the planet. he agrees, but he plans on coming back later. Havelock tries to send supplies down in one of the light shuttles, but the planetary defense system comes online and shoots the shuttle down, seemingly from some sort of cannon on one of the moons. The aliens also have some sort of dampening field that stops nuclear fusion from occurring, so all the ships' reactors go offline, forcing them to run on battery power only. Without their drives, the ships' orbits all begin to decay.

Miller appears and tells Holden he needs to use the material transfer network to get to the blind spot he's seeking out; Holden tells him “later”, after he saves everyone. Miller suggests that maybe airdrops of supplies are probably innocuous enough that the defense grid won't take them out, so Havelock begins dropping supplies that way, successfully.

To make matters even worse on Ilus, the organisms that lived in the clouds infect everyone via the rain, and they all start going blind, except Holden. Elvi and the other scientists desperately try to find a cure, and eventually Elvi realizes that Holden's anti-cancer meds are what's stopping the parasites from blinding him.

Since Havelock still refuses to release Naomi, Basia EVA's over to the Edward Israel and begins cutting through the hull. Murtry tells Havelock to get his ad hoc assault team together to stop the invaders using extreme prejudice. Havelock doesn't want things to escalate any more than they already have, and since Naomi is possibly be the best engineer to solve the fusion situation, he springs her from the brig. He takes out a few of his own team along the way with tasers and non-lethal rounds, and eventually they find Basia. They manage to get out an airlock and make it to the Roci intact.

Holden gets into a fight with Murtry, but doesn't kill him. Elvi tells Holden his anti-cancer meds are curing the blindness, and that they should all be able to see within a few hours, maybe days. After a quick nap, he finally agrees to help Miller and joins him on the material transfer system.

Basia goes EVA again and attaches tethers to the Barbapiccola so the Roci can tow her to a more stable orbit. They manage to boost it quite a ways when the Israel launches their shuttle-turned-torpedo at the Roci. Alex fires the PDCs and shreds the shuttle, but the shrapnel penetrates the Rocinante's hull, cutting multiple small holes through it, and injuring Havelock's arm. Naomi and Baz patch up all the holes, but the maneuvering thrusters on one side are all shot; Alex informs them that they're going to lose the Barb and there's nothing they can do about it. They plan to evacuate some of the crew of the Barb to the Roci, but ultimately decide to try using the railgun as a thruster. All goes according to plan and they again briefly stop the Barbs orbit from decaying; however, the Israel launches their security team EVA toward the Roci.

On Ilus, Murtry and Wei take off in the one working cart after Holden. Amos and Elvi get the other cart working and, along with Elvi's new boyfriend, Fayez, follow in their tracks. Holden passes out for about 20 hours, and when he wakes up, Miller tells him they'll have to go the rest of the way on foot. Miller takes control of one of the giant alien maintenance mechanisms and uses them to cut the door off the transit car, clearing the wreckage blocking the track. Holden climbs on its back and rides it to their destination.

They reach the processing station and Miller explains that the whole planet contains materials rare in the galaxy; it is basically an interstellar gas station.

With the Rocis PDCs down, Havelock goes EVA and tries to shoot down the attacking team and their makeshift missiles. One of the missiles finds its mark; it does only superficial damage to the Roci, but knocks Havelock off the ship and hurls shrapnel into his leg. Basia goes out and retrieves him using a grapnel. The attackers from the Israel launch some missiles at the Barb and knock it off course, also irreparably damaging the tether to the Roci. Basia heads towards the Barb and Havelock covers him.

Elvi and Amos eventually come to the enormous alien structure where Holden's at; they find Murtry's cart abandoned, the engine burned up. Inside the structure, Wei tells them they're not authorized to go any further; Amos shoots and kills her, Murtry shoots Amos in the back multiple times, but it doesn't penetrate his armor, though he does blow off some of his fingers. Amos shoots Murtry in the chest, but his armor saves him. Fayez tells Murtry this is his fault, that Amos was trying to save everyone, and punches Murtry on the nose. Elvi runs to find Holden as Murtry shoots Fayez.

While Havelock fires at the impending attackers, attempting to only disable their EVA packs instead of killing them, the chief engineer in charge of the militia continues to goad and insult Havelock and the crew of the Roci. Basia then comes up with the idea of attaching multiple inflatable airdocks together to get the people from the Barb to the Roci. The captain of the Israel agrees to give some spares so everyone on the Barb will be able to be saved before the ship breaks up in the atmosphere. The chief engineer starts yelling at the Israel's captain, saying he will use lethal force to prevent any aid being given to the "enemy". Suddenly, the chief's complaints are cut off mid-sentence and Alex admits to shooting him with the rail gun, saying he had the shot and sheepishly asking if he is in trouble. Using tethers, they successfully get all the portable docks onto the Israel; a short while later, the Barbapiccola explodes in the atmosphere. Basia is overcome with grief when he realizes the people on the Israel, the ones saving his people, were the ones he killed when he bombed the RCE shuttle.

Elvi runs through the complex and practically stumbles right into Holden and that hulking insect-like machine with him. She warns him about Murtry and tells him she thinks Amos is dead. Holden nonchalantly introduces Elvi to the alien mechanism controlled by proto-Miller and tells her and Miller to go save the planet; he goes after Murtry. They come to a chamber with a swirling vortex of darkness upon darkness that Elvi describes as "the eye of an angry God," but Miller can't see it.

Holden meets Murtry at opposite sides of a bridge; Murtry says he has to stop him from shutting down the technology because the RCE can learn from it, and even if it means he and all his people have to die, so be it. He also tells Holden that Amos and Fayez are still alive, but barely. They both prepare for a wild-west style shootout, but while Murtry is busy grandstanding, Holden shoots him multiple times in the chest, arm, and leg. Holden patches him up and saves him, then tells him that he's got powerful friends back home that owe him favors, which he plans to cash in by humiliating Murtry.

Suddenly, the machinery around them starts coming to life. Miller activates all the equipment he can, wanting to throw it all at the black thing in the center of his room. The aliens aren't happy about this and attack Miller and Elvi. She manages to avoid them by hiding behind the black hole, since they can't see it, and they kill themselves chasing after her. Miller is damaged irreparably though, so he asks Elvi to take the blue, almond-shaped unit inside him out and walk it into the dead spot. Just as the robots are about to overtake her, she slips into the dead spot. Inside, she feels herself torn apart and put back together again, then passes through the other side. Everything is dark and all the machines are off again, the dark spot remains. Miller takes control of everything, becomes the entire world. Proto-Miller stops reaching out.

Holden lets the Roci know the planet's defense system is down and Alex fires up the engines; everyone else follows suit. The Roci lands on Ilus to drop off supplies. About half the colonists on the Barb decided to stay with the scientists on the planet, and the other half opt to go back with the Israel and the Roci. Video of the rescue of the crew from the Barb onto the Israel hits the feeds back home, and Havelock and Captain Marwick are portrayed as RCE heroes who saved the colonists. Everyone on the planet is working together finally, and they might actually stand a chance at surviving. Holden and the Roci crew take off; he lets Basia stay behind with his family.

Holden takes an EVA suit and a blowtorch into the Roci's cargo bay and tears it apart until he finds the remaining bit of protomolecule. He loads it into a probe and shoots the probe into Ilus' parent star. Murtry is locked up in the medical bay, and will be tried by the UN on Luna.

On Mars, Avasarala meets with Bobbie Draper and explains that the MCR is compromised. She had planned on Holden failing, but since he didn't, the population of Mars will be leaving the inhospitable planet in droves to the new worlds. The only thing Mars will have left to sell are its 15,000 nuclear warheads.