In the outer solar system near Saturn, James Holden and the crew of the ice-freighter Canterbury, investigate a distress call from a mysterious derelict ship, the Scopuli. On Ceres Station, Detective Miller begins an off the book investigation of a missing heiress, Julie Mao.

Holden and crew are trapped in badly damaged shuttle. On Ceres, Miller uncovers clues about Julie Mao. On Earth, Chrisjen Avasarala questions a terrorist.

Holden and the crew are taken prisoner by the Martian Congressional Republic Navy. Miller deals with unhappy rioters. Avasarala plays politics and gets severely burned.

Holden and crew find themselves in the middle of a desperate battle while still aboard the Martian battleship. Miller’s partner, Havelock, goes missing.

Holden finds an unlikely ally. Miller’s obsession with Mao intensifies.

Miller gains valuable information from a hidden data cube. Holden and his crew learn their host’s agenda.

Holden and his crew face a Martian military blockade. Miller finds a new reason to forge ahead. Avasarala visits Holden’s family.

A derelict vessel holds a potentially devastating secret. Holden and his crew cross paths with Miller on Eros. Avasarala receives bad news.

Julie's origin story ends up revealing her trajectory. Holden and Miller work together as they take a look at a strange emergency happening on Eros.

Avasarala uncovers a game-changing secret while the future of the human race might be in Holden and Miller's hands.

Unlikely allies Joe Miller and the crew of the Rocinante led by Jim Holden uncover more about the conspiracy to release the protomolecule on Eros station.

With the help of Fred Johnson and the OPA, Miller, Holden and the crew stage a raid for information on the protomolecule. On Earth, Avasarala learns a truth about Fred Johnson.

Holden and Miller butt heads about how the raid was handled.

Miller devises a dangerous plan to eradicate what's left of the protomolecule on Eros.

The Rocinante chases an asteroid as it hurtles towards Earth.

Earth and Mars search for answers in the aftermath of the asteroid collision.

Preparations for the Earth/Mars peace conference tighten the tension on Erringwright.

Naomi tracks down signs of the protomolecule; Fred Johnson's control over the OPA collapses.

Bobbie becomes a political pawn in the struggle between Earth and Mars.

Holden leads his crew through the war-torn station on Ganymede.

Bobbie makes a decision that changes her life forever.

A discovery pushes Naomi and Holden apart and sets the Rocinante crew against each other.

The Rocinante crew must fight to save the ship.

The Rocinante crew deals with the fallout over Naomi's betrayal while caught in the middle of the war between Earth and Mars while Avasarala and Bobbie hatch an escape plan.

The Rocinante answers an unexpected distress signal. Bobbie and Avasarala find themselves being hunted by a mysterious captor. UN Secretary-General Sorrento-Gillis brings in a colleague from his past to lend an ear during this crucial time of war.

As Earth strategizes a costly ploy to gain advantage in the war against Mars, Anna struggles to convince Sorrento-Gillis to do the right thing. Avasarala and Bobbie seek refuge aboard the Rocinante.

The Rocinante tends to wounded Martian soldiers in exchange for supplies. Avasarala struggles with how to disseminate a key piece of evidence despite being in hiding.

The search for Prax's daughter comes to a head. Admiral Souther's men plan for mutiny aboard the Agatha King

The final battle between Earth and Mars threatens the very future of humanity. A new monster is unleashed on Prospero Station. Anna receives the smoking gun she needs.

All eyes turn to the edge of the solar system as a mysterious new presence emerges; Naomi recommits to her roots; Drummer butts heads with a seasoned new commander aboard the Behemoth; and a young Belter makes a name for himself.

An old friend taunts Holden with the answers he seeks. Naomi struggles to fit in. A mysterious low-level tech aboard the Thomas Prince enacts a terrifying plan.

The Rocinante seeks a new gameplan as they attempt to avoid capture. Melba's true motives are revealed. Naomi is torn between identity and ideal. Anna seeks a way to stay aboard the Thomas Prince.

Holden sees past, present, and future. A ghost from Melba's past threatens her mission. Bobbie struggles to trust an old friend as she leads a group into unchartered territory.

Drummer and Ashford find themselves trapped with few options for survival; Anna tends to the wounded masses as Melba continues to hunt down her prey; the Rocinante crew struggles to survive as Naomi reunites with her true family.

As survivors arrive to the Behemoth, two factions form over how to handle a life-or-death threat. Holden grapples with what he's seen and the choices he must make.

Holden and his allies must stop Ashford and his team from destroying the Ring, and perhaps all of humanity.

The crew of the Roci investigates a strange protomolecule ruin on an alien planet. Bobbie copes with civilian life on Mars. Drummer and Ashford battle with piracy in the Belt.

Avasarala is blindsided while on a visit to Mars. The Roci crew continue their protomolecule investigation while tensions between the RCE and Belters reach a tipping point. Drummer and Ashford track down a terrorist.

New alien threats emerge on Ilus as Naomi battles health challenges on the planet. Bobbie searches for a missing person on Mars. Avasarala faces a new challenge in the UN.

Drummer and Ashford confront a dangerous person from Naomi's past. Murtry hunts down a target. Bobbie's makes a life-changing confession.

As tensions on Ilus reach a boiling point, Holden reveals a secret. Avasarala debates Nancy Gao while an emergency on the Roci forces Alex and Naomi into action.

The Roci crew prepares for an incoming disaster on Ilus. Ashford and Drummer close in on an enemy within the Belt. Bobbie takes on a dangerous job.

Naomi and Alex work to keep the Barbapiccola in orbit amidst a power outage. Avasarala faces a tough decision. Holden and Elvi race to find a cure for a disease spreading on Ilus.

Avasarala faces fallout for the UN's military mission. Ashford and Drummer makes big decisions about their future within the OPA. A spreading illness on Ilus takes a toll on Amos. Alex and Naomi's attempt to rescue the Barb turns desperate.

Holden and Miller race to save Ilus. Murtry puts his endgame into motion, putting the Roci crew's lives at risk.

Ashford closes in on an enemy while uncovering a dangerous plot. Avasarala faces a crossroads in her personal and political life. The Roci crew works to reestablish life on Ilus in the wake of a deadly catastrophe.

Holden tries to convince Fred Johnson to destroy the last sample of protomolecule. Naomi gets an important lead to her son. On Luna, Avasarala begins to hunt for Marco Inaros.

Holden and Fred deal with infiltrators on Tycho. Drummer's past comes back to haunt her. Amos returns to Baltimore. Alex and Bobbie's investigation on Mars leads to rogue soldiers.

Naomi comes face to face with Filip. Holden and Fred turn the tables. Avasarala closes in on Marco's plot.

Marco's grand plan shocks Earth, Mars and the Belt.

Amos and Clarissa are trapped in a collapsed building. Naomi contends with her old family. Holden assembles a new crew on the Roci. Alex and Bobbie make a dangerous discovery in the Belt.

Holden and the Roci go on the hunt. Amos and Clarissa seek shelter on a devastated Earth. Bobbie and Alex fight a desperate battle. Marco makes Drummer an offer she can't refuse. Avasarala returns to a position of power.

Naomi makes a desperate attempt to save her son from Marco. On the Roci, Holden battles for the last sample of protomolecule.

Amos returns to Baltimore with Clarissa. On Luna, Avasarala's alliances begin to shift. Alone and adrift, Naomi becomes a deadly lure.

Amos, Clarissa, and a gang of thieves work together to leave Earth. Avasarala tries to head off a brutal military strike. Drummer's new family bonds are tested as Naomi's life hangs in the balance.

Holden and the Roci face off against Marco's forces and Drummer, while Alex and Bobbie attempt a dangerous rescue of Naomi, and the balance of power in the Solar System shifts.

The Rocinante crew make a startling discovery on an asteroid. Avasarala and Bobbie contend with the devastation on Earth. Drummer and her family must make a heartbreaking decision. On Ceres, Marco and Filip's struggles turn inward.

With an unexpected passenger aboard the Rocinante, Holden and crew undertake a dangerous mission that could shift the balance of power in the war. Drummer decides to make an uneasy alliance. Filip wrestles with his guilt.

Avasarala, with the Combined Fleet of Earth and Mars, takes the war to Marco. Filip and Marco's relationship is tested. The war becomes more perilous and personal for Holden and Naomi when the Rocinante is suddenly forced into a battle.

Holden finds himself at odds with his crew when a controversial decision is uncovered. On Ceres, Avasarala struggles to contain an escalating humanitarian crisis. Drummer's growing faction stage a daring raid with dire stakes. Filip, demoted to repair skiff duty, makes an unexpected discovery.

Paths converge on Ceres when Drummer and her fleet arrive to aid the relief effort. Holden tries to convince Avasarala to release crucial information that might avert catastrophe, but she has her own request of him. As Amos and Bobbie get a little R&R at the station, Naomi has a difficult and long-awaited reunion.

In the thrilling season finale, Inners and Belters fight side by side with the crew of the Rocinante in a last, massive, desperate battle with Marco and his Free Navy, with the fate of the Solar System, the Ring Gates, and of all humanity hanging in the balance.