The Expanse is a television show based on the novels by James S.A. Corey. Every week, I’ll be taking a look at one moment in each episode of the show’s second season, and chatting with the creators about how it was created and what it means for the larger story.

Spoilers ahead for the final two episodes of season 2, “The Monster and the Rocket” and “Caliban’s War.”

With this week’s episode, “Caliban’s War,” The Expanse’s second season wrapped up. It’s been an interesting, sometimes bumpy ride to this point. The show has taken us to Jupiter’s moon Ganymede, where the crew of the Rocinante has been working to help a biologist named Prax find his missing daughter in the aftermath of a battle, only to discover that Protogen’s protomolecule experiment has taken on a sinister turn. The company responsible for seeding Eros with the alien bug in season one turns out to have infected children to turn them into weapons, like the one that attacked Bobbie and her team earlier in the season.

In the last two episodes of the season, Holden and Prax hitch a ride on the Rocinante, and track down one of the protomolecule hybrids, which has escaped onto the surface of Ganymede. They’re doing everything they can to kill it before it escapes.

Meanwhile, Alex and Naomi work to evacuate a bunch of refugees from the planet’s surface, but have more people than they have space. Once they take off, they’re under threat of being shot down by the Martians. This is where the Roci’s crew have to make a decision: save Naomi and a bunch of refugees, or continue their pursuit.

Unfortunately, the season’s final episode negates that choice, because the crew discovers that the hybrid is on the Roci. When Holden and Amos try and kill it in the ship’s hold, Holden gets pinned down, prompting the crew to consider drastic measures to get the creature off the ship. Prax hatches a plan to lure it out in a scene ripped right from Alien.

Elsewhere in the system, Chrisjen Avasarala, Bobbie, and Avasarala’s bodyguard Cotyar go to meet Jules Pierre-Mao, the man responsible for the protomolecule, to negotiate his surrender. Instead, they also get pinned down. Bobbie gets a couple of great moments as she dons her Martian power armor and throws some people into the walls. A third storyline follows a ship orbiting Venus as the UN and Martian governments investigate the remains of Eros, which crashed into the planet. While the various story arcs seem separate, series co-author and executive producer Daniel Abraham says they’ll come together in the coming season.

While this season continued to demonstrate that the people behind The Expanse are astute observers of human pack behavior, the show still has structural issues. While the series and show tell an ongoing story, the self-contained stories in Leviathan Wakes and Caliban’s War are a stumbling block as the show shifts from one arc to the next. Abraham says shifting between novels was a challenge. “The end of Miller's arc and the beginning of Prax and Bobbie's stories had to be feathered together in a way that having Thomas Jane fade out of the story didn't make it feel like the whole story was just over.” The result was a gap between arcs.

With the show renewed for a third season, we’ll likely see the same situation, as the show wraps up Caliban’s War and moves toward Abbadon’s Gate, the third novel in the series. Abraham says, “We have built up some strategies that will serve us well when we start moving into the next transitions between books.”

In spite of some structural story awkwardness, The Expanse shines when it sticks with its roots by spotlighting human tribalism. Because the show didn’t have to introduce itself this time around, it was able to jump right out of the gate and into the story, and this latest batch of episodes double down on exploring the moral complexity of the players in its system. While all three factions have noble intentions — Earth wants to hold the solar system together; Mars wants to build a habitable planet for its citizens; and the OPA is working to ensure that its people have a voice, and air to breathe — each will also go great lengths to get their way. Earth butchers rogue stations, Mars seeks out the protomolecule hybrids, and the OPA spaces innocent civilians because they’re from Earth or Mars.

The Roci’s multi-ethnic crew serves as a solid message that cooperation between racial and social groups isn’t just possible, it’s a blueprint for survival. As characters cross the boundary lines that history has established, we see that the infighting prevents humanity as a whole from surviving, especially in the face of a threat from an alien superbug that could wipe humanity from the system. Even then, those boundary lines are hard to cross: in the finale, we learn that Naomi turned over a sample of the protomolecule to Fred Johnson, rather than destroying it by shooting it into the sun.

These threads will likely continue into the third season. Abraham says that the show’s writer’s room has outlined the season, and that it’ll “move ahead with stories that are true to the spirit and broad strokes of the books,” with some changes to better fit the medium. “I'm very excited by how season three has laid out.” Production has already been booked for Toronto, with cameras set to roll this July.

By the end of the season, The Expanse has certainly earned a place as one of the best science-fiction shows to air on television, ranking alongside Battlestar Galactica, Babylon 5, and even Star Trek. It’s smart television, that just needs to find a way to streamline its story. Season 3 is due out in 2018, and I already can’t wait to see what happens.