Season 4

Complete listed story — includes the ending

S4E1 · New Terra

Avasarala orders a blockade of settler ships near the Ring, wary of the risks of expansion. A convoy of Belter refugee ships from Ganymede attempts to run the blockade; of the few that succeed, the Barbapiccola lands on a planet named "Ilus" which features prominent alien structures. Avasarala sends Holden there as her envoy, with the rest of his crew joining him, in order to identify any potential protomolecule exposure. Naomi begins taking brutal drugs in order to develop a tolerance to high gravity. On Mars, Bobbie dismantles decommissioned warships for a living, discontented with her plight. With a truce between Earth, Mars, and the Belt in effect, Ashford operates as an OPA peacekeeper, tracking down and neutralizing renegades; Drummer commands the former Behemoth, now renamed Medina Station, which controls the Ring Space. The Earth ship Edward Israel, ferrying a Royal Charter Energy (RCE) expedition backed by Earth and Mars, sends a shuttle to Ilus that is destroyed during its landing; many lives and supplies are lost. The Rocinante crew arrives amid tensions between the surviving shuttle passengers and the Belter settlers that escalate into an armed standoff; it is interrupted when a swarm of alien "bugs" attacks the settlement.

S4E2 · Jetsam

Avasarala visits Mars and invites Bobbie to a state banquet. At the banquet, Bobbie is rebuffed by fellow Martians and offended when she perceives that she is being used by Avasarala; she rejects a job offer from Avasarala. Bobbie discovers that her nephew, David, is preparing illicit "focus drugs" for a gang. She ends his involvement by beating up the gang members and destroying their lab. On Ilus, the Rocinante crew navigates the ongoing tensions between the Belters and Earthers; they identify the bugs as protomolecule-based. The drugs Naomi has been taking have not been fully successful. RCE Security Chief Adolphus Murtry, who took charge after the expedition's leader had died, identifies the shuttle's downing as deliberate; he confronts Belters about that and kills one of them in a standoff. Holden, guided by Miller, enters an alien structure near the settlement and removes a root growing through a panel, activating the structure; this triggers a pattern of lightning strikes across Ilus. Amos begins a relationship with Chandra Wei, Murtry's second-in-command. On Medina, Ashford and Drummer investigate the disappearance of the UN colony ship Sojourner and find it was stolen by Marco Inaros, an OPA pirate and Naomi's former lover.

S4E3 · Subduction

On Earth, Nancy Gao, a former UN Home Secretary who has resigned from Avasarala's cabinet due to the disagreement over her blockade strategy, runs for UN Secretary General against Avasarala on a pro-expansion platform. Avasarala's aides uncover a nepotistic scheme that benefited Gao in her career; Avasarala has evidence of it discreetly leaked. On Mars, Bobbie learns that the gang has kidnapped David and forced him to work off the debt incurred from her destruction of their lab. Detective Esai Martin, the gang's ringleader, agrees to release David if Bobbie helps them steal military equipment from her workplace. After she eventually complies, Esai releases him. She declines Esai's offer to join his gang. On Ilus, lightning strikes the settlement, damaging the Belters' power generation infrastructure; Amos and Naomi help them repair it. Murtry identifies the Belters responsible for the downing and orders their execution. Holden, accompanied by Alex and RCE biologist Dr. Elvi Okoye, finds another alien structure that was activated; it is displacing wide swathes of ground while moving toward the settlement. Despite Okoye's protests, Holden has Alex destroy the structure with a torpedo from the Rocinante.

S4E4 · Retrograde

Drummer and Ashford apprehend Marco Inaros for stealing the Sojourner and executing its passengers. Drummer, Ashford and three other OPA faction leaders hold a trial for Inaros; he appeals to Belter solidarity, offers them the money he made from the Sojourner and promises to abide by the truce with the Inners. They acquit him by the three to two vote; Drummer, who votes last, chooses to acquit him to prevent division among the OPA, despite hating Inaros for hurting Naomi. On Mars, Bobbie quits her job after attempting to report material theft to her supervisor, only to find out that he is interested in selling more stolen goods. Shortly after, she is arrested for abetting the crime, presumably at the direction of her supervisor. Her charges are dropped once she accepts Esai's offer. On Ilus, Naomi tries to help Dr. Lucia Mazur, a Belter complicit in the downing, escape from Murtry and his forces; Amos gets arrested by Murtry while helping them. Murtry eventually backs down when Holden and Alex intervene and fire the Rocinante' s PDCs at his forces. Naomi, Alex, and Lucia go into orbit aboard the ship while Holden remains on Ilus.

S4E5 · Oppressor

Avasarala and Gao's first public debate, during which Avasarala's attempt to use accusations of nepotism against Gao backfires, is cut short by a security threat; an unidentified ship, initially claiming to be a civilian ship experiencing a system failure, has diverted course toward an Earth asteroid defense platform and gone silent. After the ship is identified as the Sojourner, Avasarala orders its destruction. On Ilus, the Earthers and Belters face off in a tense showdown. Holden reveals his alien connection and reactivation of the alien technology to the settlers to convince both factions into leaving Ilus, but it only further inflames the situation. However, Murtry releases Amos as he also wants Belters to leave Ilus and perceives that his interests are now aligned with Holden's. Lucia and her husband, Jakob, have an argument over her part in the downing of the RCE shuttle and their family falling apart. Feeling guilty, Lucia attempts suicide; Alex saves her, and Naomi counsels her on dealing with guilt, drawing from her own past. An island on the other side of Ilus explodes, causing a shock wave to begin traversing the planet's surface.

S4E6 · Displacement

Alex and Naomi inform Holden of the explosion and an impending earthquake; it will be followed by a shock wave, and then a tsunami that will destroy the settlement and flood the continent. Once privy to this knowledge, the settlers finally consent to evacuate Ilus; the Belters only do so after Holden agrees to vouch for their claim on the planet to the UN and Avasarala, which antagonizes Murtry. The explosion prompts Ilus' defenses to shut down the fusion reactors on orbiting ships; the evacuation shuttle from the Israel gets incinerated mid-descent. Unable to leave the planet, the settlers take shelter in the nearby alien structure; some are killed by the shock wave during the evacuation; the surrounding area gets flooded. On Mars, Bobbie succeeds in her new job for the gang. During a heist, she risks her life to complete the mission, impressing Esai. UNN officers visit Medina and criticize Drummer for mishandling the issue of the Sojourner and Marco Inaros. Drummer and Ashford receive evidence that Inaros is involved with someone on Mars and that he is currently on the Belter ship Pizzouza.

S4E7 · A Shot in the Dark

On Ilus, the Earthers and the Belters set up separate camps inside the alien structure. Everyone besides Holden, who is immune, has been infected with microorganisms that are growing in their eyes; Okoye determines that the microorganisms will cause blindness. Settlers also start being killed by neurotoxic "slugs" that are growing along and crawling out of the structure's walls from the Ilus oceans. Murtry plans to outlast the Belters and plots against Holden. Amidst the fusion shutdown, Lucia devises a solution to keep the Barbapiccola from falling out of orbit: tethering the ship to the Rocinante. On Earth, Avasarala is upset over her dwindling support in the poll numbers. After receiving the video evidence of Inaros' location from the OPA, she orders a team of UN marines to board the Pizzouza and capture Inaros alive with minimal casualties, but he is not found; a firefight breaks out before the ship explodes, killing everyone aboard.

S4E8 · The One-Eyed Man

Avasarala is condemned over the Pizzouza' s destruction. In order to salvage her reelection campaign, she leaks images of the environmental disasters on Ilus, but gets confronted by her husband Arjun for putting her pride above the interest of others. Drummer resigns from her position, upset over Fred Johnson giving the evidence of Inaros' location to Earth. Ashford plans to independently hunt down and kill Inaros; Drummer, weary of politics, declines Ashford's offer to join him. On Mars, with the gang's upcoming job paying a lot and having many unknowns, Bobbie raises her concerns to Esai, but he discounts them as he needs money to make his family's life better. The crews of the Rocinante and the Barbapiccola successfully tether their ships to one another. In the alien structure, the settlers are all blind now, except for Holden; more Belters die when they wander off. Amos has a nervous breakdown over his powerlessness. Okoye determines that Holden is immune because of his anticancer medication (which he has been taking since absorbing radiation on Eros). She prepares a cure and the settlers regain sight. Holden finally sees Miller again, but Miller appears to be glitching in and out.

S4E9 · Saeculum

Murtry has the Israel launch a weaponized shuttle at the Rocinante. Alex destroys the shuttle, but the resultant debris damages many of the Rocinante's thrusters; Lucia is knocked into space but is saved by Naomi. Alex uses the ship's railgun as a makeshift thruster to maintain orbit. Miller, who can now intermittently overcome his protomolecule programming, leads Holden to an artifact that can shut down all of protomolecule activity on Ilus; this artifact, having the form of an energy circle, was presumably left by the species that killed the protomolecule's creators. Murtry and Wei follow Holden, but they are in turn followed by Amos and Okoye. Wei confronts Amos; when neither stands down, Amos kills Wei while Murtry shoots and disables Amos, blowing his fingers off. Okoye finds Holden near the artifact and tells him what happened. Holden goes back for Amos and confronts Murtry; after a standoff, Holden manages to disarm Murtry, though both are wounded. Miller communicates with Okoye and creates a metal mechanical body for himself to go through the energy circle. Despite the structure's attacks on them, Okoye helps Miller reach the artifact, through which they both fall.

S4E10 · Cibola Burn

Miller is gone, having successfully stopped all of protomolecule activity on Ilus; the ships in orbit get their power back. Murtry and Amos recover aboard the Rocinante. The settlers on Ilus decide to stay, planning to rebuild the settlement together and continue research. Murtry and Lucia are to stand trial for their respective crimes, but Holden sets Lucia free. While the Israel remains in orbit, the Rocinante and the Barbapiccola head back to the Solar System. Holden destroys the last piece of protomolecule still on the Rocinante, which Miller had informed him of. On Earth, Gao wins the election; Avasarala is being sent to Luna but Arjun, still angry with her, stays on Earth. On Mars, Bobbie's gang gets ambushed; Esai and most other members are killed. Bobbie notifies Avasarala of Martians trafficking military weapons with Belters and accepts her job offer. Ashford learns of the trafficking himself before finding Inaros and boarding his ship. After a firefight between their crews, Ashford corners Inaros, only to be ambushed by Filip, Inaros' second, and his and Naomi's son. Inaros kills Ashford, but unknown to him, Ashford has recorded their last conversation and hidden the recording for later discovery. Inaros launches asteroids cloaked with Martian stealth technology at Earth.