The Expanse Season 4 Is Almost Here, So Here's A Crash Course On Where The Sci-Fi Standout Left Off

The Rocinante crew looks to be making yet another tough decision in this shot from season four. (Image: All images Amazon Studios)

The Expanse premieres its fourth season (thank you, Amazon) on December 13, which means you technically still have time to re-watch seasons one through three. But if you don’t have several dozen spare hours between now and next Friday, we’ve got a handy primer to remind you of exactly where things stand.

A quick note, though: If you’ve never seen The Expanse, or still have some catching up to do, you should really take the time dig in before you watch season four. It’s not because season four is indecipherable to new arrivals, but because it’s so much more enjoyable to witness if you know the full history and nuances of the various storylines.

Also, The Expanse is just so incredibly fun to watch; it’s got political and military intrigue, outstanding space battles, sci-fi mysteries, an unusually respectful approach to actual science, striking production design, and plenty of high-stakes conflicts, all brought to life by fascinatingly complex characters. And while many of those characters will be facing a new world in season four, it’s been an epic adventure to get to this point.


Avasarala has the best wardrobe on this show, or any show.

What it’s about

Based on the novels by James S.A. Corey (a.k.a. Daniel Abraham and Ty Franck, who are also among the TV series’ producers), The Expanse is set 300-ish years in the future, in a time when humans live on Earth, Mars, and “the Belt,” space stations and asteroids. Tensions run high between all three.

Earth is still seen as the dominant power, but it’s a polluted shell of its former glory, where unemployment plagues most of the population and even the non-corrupt politicians must resort to subterfuge to push their agendas. Mars has a tremendous military presence, but the planet itself is still undergoing the agonizingly long process of being terraformed. The Belt, meanwhile, is viewed by Earth and Mars as second class; its people perform undesirable dirty jobs gathering resources for “the inners.” It has a rebellious culture that gave rise to the Outer Planets Alliance, or OPA, long viewed as a terrorist group—though as the show’s progressed, a more diplomatic Belter State has also emerged.

Miller dies heroically in season two but later returns as “The Investigator.”

What’s happened so far

As The Expanse begins, a mysterious “protomolecule” is discovered on Phoebe, one of Saturn’s moons. The secrecy surrounding the protomolecule drives the first two seasons, as all the characters try to understand what they’re dealing with and who’s pulling the strings. Danger abounds, as spooky stealth ships start turning their weapons on anyone who gets too close to the truth, and an entire asteroid, Eros, is overtaken by what appears to be a horrific new plague before crashing into Venus, narrowly bypassing Earth in the process.

At first, nobody can figure out if Earth, Mars, or the Belt is to blame, but we come to learn that an Earth billionaire, Jules-Pierre Mao (François Chau) aided by shifty politicians hellbent on war (first from Earth, then Mars, then back to Earth), has made the protomolecule his pet project. He plans on weaponizing it and using it to create hybrid super-soldiers, with kidnapped children as test subjects.

But the “blue goo,” which is actually ancient alien technology of sorts, is not a substance that can be controlled. It has its own agenda, and abilities far beyond what any human can comprehend—and by the middle of season three, it’s no longer a secret. The Eros wreck on Venus eventually transforms itself into a space structure that comes to be called “the Ring,” a baffling, terrifying, and tantalising cosmic phenomenon that briefly unites humanity (very, very briefly; the age-old rivalries soon return) as it faces its greatest-ever unknown.

Naomi (and her new hairdo!) in a shot from season four.

Who’s who

The Rocinante crew: the captain, Earther James Holden (Steven Strait); the engineer, Belter Naomi Nagata (Dominique Tipper); the mechanic and the muscle, Earther Amos Burton (Wes Chatham), and the pilot, Martian Alex Kamal (Cas Anvar). Brought together by chance in season one—they were the sole survivors after the ice hauler they were all working on, the Canterbury, was destroyed as part of the vast conspiracy surrounding the protomolecule—they acquire a sleek Martian gunship (renamed the Rocinante) and immediately find themselves on the front lines, trying to serve the greater good as Earth, Mars, and the Belt teeter on the brink of war. They don’t always see eye to eye, but their shared experiences have made them a tightly bonded group.

Miller/The Investigator: In seasons one and two, Miller (Thomas Jane) is a rough-around-the-edges Belter cop who becomes obsessed with a missing-person case—Mao’s daughter, Julie (Florence Faivre)—that ties into the protomolecule discovery; that’s how he ends up crossing paths with the Roci crew. After he sacrifices himself to help steer Eros away from Earth, Miller is presumed dead on Venus—until he pops back up in season three as “the Investigator,” a figure assembled by the protomolecule as a way to speak with James Holden. His guidance is crucial to navigating the Ring, but his conversation style is frustratingly cryptic, as are his motivations.

Chrisjen Avasarala: A glamorous, whip-smart, and delightfully foul-mouthed Earth diplomat, Avasarala (Shohreh Aghdashloo) is fiercely protective of her planet, but she doesn’t believe in senseless war—especially, as she comes to discover, when it’s built on lies propagated by unscrupulous colleagues and their wealthy associates. After spending part of season three running for her life in space (where she encounters the Roci crew), she’s finally able to communicate the truth about who’s behind the protomolecule project—and returns home as the heroic new leader of Earth.

Bobbie Draper: When we first meet Bobbie (Frankie Adams) in season two, she’s a deeply patriotic, tough-as-nails Martian Marine. Her toughness never falters, but her single-minded devotion to Mars does when her team is killed—collateral damage as part of a protomolecule weapons test—and she’s forced to deliver false testimony about it, then gets booted from the service for trying to tell the truth. After she defects to Earth, she helps Avasarala escape from Mao’s space yacht and then helps the Roci crew overtake his illicit facility for creating protomolecule-infused soldiers. That mission also sees the Roci crew, with help from the Belt, save Mars from a protomolecule invasion launched by one of Mao’s Earther cronies. Her heroism gets her reinstated in the Martian Marines...at least until the end of season three.

Camina Drummer: The petite but badass Belter (Cara Gee), formerly the second in command at Tycho Station, ends up captaining the Behemoth, a giant colony ship commandeered by the Belt and transformed into a warship. But while the new Belter State presents a unified front to “the inners” in season three, behind-the-scenes squabbles between OPA factions mean Drummer’s command is precarious at best. The First Officer aboard the Behemoth is onetime pirate Klaes Ashford (David Strathairn), whose loyalties and methods are a bit suspect. He briefly takes over as Behemoth captain when Drummer is catastrophically injured—but she recovers, and the Belter pair manage to strike an uneasy truce by the end of season three.

Holden’s unique link to the Ring builders sets him apart from everyone else.

Where things stand

Season three of The Expanse contains portions of two Expanse books, which means there are two thrilling storylines with a midseason time jump of several months in between. In the second half of the season, the Ring suddenly “wakes up” when a brazen Belter crashes through it; under advice from the Investigator (who is visible only to Holden), the Roci enters as a way to dodge a torpedo launched by the Behemoth after Holden is framed for blowing up a UN ship on behalf of the Belt. Holden and the Investigator then head to the glowing blue puzzle box of a “station” at the centre of the Ring with Martian Marines, including Bobbie, in pursuit. It is all, as Amos puts it, a lot of “weird shit,” and it only gets weirder from there.

Once inside the station, Holden receives a dazzling yet horrific message from the ancient beings that created the protomolecule; it shows dozens of portals emanating from the Ring and a vision of an entire civilisation being annihilated. As a shell-shocked Holden explains, “We are in a graveyard. We need to get out of this place and never come back.”

But a hasty escape is impossible, since all the ships within the Ring are held in its inscrutable force field. A seemingly promising plan to blast through the Ring only antagonizes it, and the Roci crew must frantically warn everyone that the follow-up plan to blast the station itself will cause the Ring to destroy all the ships within it—before turning on the entire solar system outside the ring, too. Finally, all the ships (Earth, Mars, and the Belt’s Behemoth) power down, demonstrating that they pose no threat to the Ring.

In response, the Ring peacefully opens hundreds of gates, portals to 1,300 habitable systems. “A new frontier,” Holden calls it, reflecting on humanity’s irrepressible urge to explore, “It’s gonna be another blood-soaked gold rush.” In a vision, Holden and Miller share a moment on a beach, looking up at the portals. “The civilisation that build the Rings is gone. Wiped out. What could have killed them?” Holden wonders. The Investigator responds: “That’s what I’d like to know. Gonna need a ride...”

The stage is set for season four. We’ll follow the Roci to one of those new systems, partially to see how humans fare when trying to settle a planet on that new frontier—but also to do a lot more digging into Miller’s “case.” 

The Expanse season four hits Amazon Prime on December 13.


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