What's the plot of Season 4?
At the end of Season 3, the world of The Expanse got blown wide open by the manifestation of multiple portals (past the initial Ring) that serve as gateways to other solar systems with habitable planets. While the series has always been focused on the political, now it's edging into Space Western territory as humans rush to colonize other habitable planets and compete over their resources. The first (and most important thus far) of these worlds is Ilus, the planet where a large part of Season 4 will take place. We'll see the crew of the Rocinante on a U.N. chartered mission to Ilus, beyond the reaches of the Ring Gate.
"You've got an entire species and several societies that have defined themselves on the fact that the solar system is all they've got, that those resources are what they have," series showrunner Naren Shankar told Entertainment Weekly. "But suddenly that all changes. It's like the discovery of the New World — suddenly there's land, there's resources, there's the potential of making incredible fortunes right there."
For those familiar with the original book series, Season 4 will loosely adapt Cibola Burn, the fourth novel in the series. The novel takes place entirely on Ilus, but Shankar was clear that Season 4 won't leave Earth, Mars, and the Belt behind. Additionally, the looming mystery of the dead alien civilization that created the protomolecule will still be at the forefront in the season. Shankar told EW that the writers are drawing not only from the main series novels but also from assorted novellas written by series authors Daniel Abraham and Ty Franck. That means that characters like Bobbie or Avasarala won't necessarily fall to the wayside despite limited appearances in Cibola Burn.