One of the great advantages of being a major power in the universe of the Expanse is that nothing truly catastrophic ever happens. Earth may struggle with its economic difficulties, its lack of opportunities for its citizens, but even in the military conflict with Mars, the home world was never affected. The same is true for Mars - it may no longer seem like the great dream, dreamed by generations, to turn Mars into a planet that has breathable air and arable land, but still, the closest that all of the chaos and nightmares of the past have come to the planet is those Marines on Ganymede. Elsewhere, millions are displaced and seeking shelter and a life, millions were killed on Eros and Ganymede, but Mars and Earth have always been blissfully save from any of the fall-out of the conflicts it has wrought.
Avasarala correctly predicts that the narrative emerging from Ilus - Belters and RCE personnel working together to establish a new settlement, Holden returning victorious (after allowing Lucia to return to her family and covering up her crimes) will play right into Nancy Gao's election campaign. The story emerging from the new planet across the ring gate is one of hope, not of defeat. And she is correct, and loses the election to a candidate who is running on a platform to colonize all these planets, even though nobody has any clue about who the species is that has destroyed the creators of the gates. As she says, in her concession speech from Luna - "One of us is wrong. I think it's you, but I hope it's me". The Rocinante returns with its mission fulfilled, Felcia will get to study, and Amos takes revenge for Murtry making him kill a woman he liked, for a bit (always good at interpreting orders, he knows he gets to punch back as long as he's not the one who is throwing the first punch). Holden and Naomi send the rest of the protomolecule which has been hiding on the Roci into a sun - but is it really the last of the protomolecule?
And elsewhere, Ashford is eager to capture Marco Inaros, after watching him capture some asteroids which he assumed he will thrown on Medina on Tycho station. He boards the ship, only to find himself overwhelmed by none other than Filip Inaros, Naomi's lost son, who regards his father like a god. Ashford is a stand-out character on this show especially because he knows that his view of the world is outdated - and instead of doubling down, he constantly tries to readjust, tries to re-integrate his values with the world he finds himself in. Except now it seems that reality has outrun him, and, as Marco tells him before spacing him, the Belters have always had little dreams, and his little asteroid - masked with Martian stealth technology - is heading straight towards Earth.
Because, on Mars, Bobbie is the one who realises that their new mission which has an unknown goal has a connection to the upper echelons of the Martian military and the science team working on the protomolecule. She realises that they are heading into darkness just before the catastrophe happens - Esai dies, Leelee is heading off planet, and Bobbie contacts a now powerless Avasarala accepting her offer of cooperating right after an unknown Martian ship is lost to the great conspiracy. Mars is a planet that has existed based on a great, unfulfilled promise - but what will happen if that promise is fulfilled elsewhere, perhaps beyond the ring gates, powered by unimaginable technologies?
