The CW’s The 100 is a bit of a Trojan horse as far as television shows go. It invites viewers in with the promise of post-apocalyptic YA action-adventure, then sneaks in impossible moral conundrums, built around a simple thesis: “Who we are and who we need to be to survive are very different.” The show is set 97 years after a nuclear apocalypse, as the descendants of survivors living aboard a clutch of international orbital stations learn that their home is running out of oxygen. The human race is headed for extinction if they can’t move back to Earth. So to determine whether the planet is survivable, they send down their most dispensable population, their juvenile offenders.

The good news is that Earth is survivable. The bad news is that it’s populated by the warlike, tribal descendants of those left behind after the bombs dropped. Those survivors have morphed old technology into a brutal, bloody religion that’s particularly hostile to outsiders. Each new season of the show is a self-contained chapter testing the boundaries of human resilience and moral relativism.

The fourth season ended in 2017, with a second environmental apocalypse that scattered the characters. The fifth season, which launched in late April 2018, begins a full six years later, and focuses on slowly bringing them back together. The premiere, “Eden,” chronicles the discovery of a valley that somehow avoided the new calamity. The journey to it is a rough and singular one for female lead, Clarke Griffin. This posed some interesting writing and production challenges for executive producer Jason Rothenberg.

“First of all, there’s no dialogue, so we’re writing the script, and there’s just description for endless, endless pages,” Rothenberg says. “Of course there’s voiceover, but a voiceover is something I tend to write as a running monologue. It was a challenge. It was exciting, like writing a movie. Production-wise, it’s also totally different. We actually took a small skeleton crew, the rover, and Eliza [Taylor, who plays Clarke] to a place called Ashcroft, about a hundred miles outside of Vancouver. We were literally in a place that was just ravaged by a forest fire. That’s why there’s so much scope to that series of scenes. It was tragic for the area, but it turned out to work in the show’s benefit because it feels like a world that’s just been burnt out. It’s something a premiere episode affords you, because you have a little more money, a little more time, et cetera.”

In The 100’s fifth season, Rothenberg plans for the character dynamics to shift tremendously, both in flashbacks and in the current story. Since season 2, the relationship between space-born Octavia (Marie Avgeropoulos) and grounder Indra (Adina Porter) has been one of the show’s cores. Like many characters in The 100, they started out in an adversarial relationship, and eventually found mutual trust and love. By the fourth season finale, they’ve developed a mother / daughter-style bond. Season 5’s latest episode, “Red Queen,” examines their relationship as Indra’s birth daughter, Gaia (Tati Gabrielle) is thrown into the mix.

“Episode 2 was a really, really hard episode to get right, and took a long time,” Rothenberg says. “We broke it and rebroke it and rebroke it again. It was important for me to have Indra with these — almost two — daughters. At the beginning of 502, the way [Indra is] trying to guide Octavia is rubbing her actual daughter, Gaia, the wrong way. Throughout the course of the season, that continues. Indra’s journey this season is really interesting, and ultimately, she’s going to have to reckon with what she’s created in Octavia. Gaia plays a big role in that, too. Gaia recognizes that the people need a commander, but her beliefs are firmly rooted in the tradition of the Flame [an AI the grounders worship as a cornerstone of their religion], so she’s not just going to stand by and let someone be a fake Commander.”

“I think Tati found levels as an actress,” Rothenberg says “She’s so young and so naturally good, but we pushed to ground her even in her voice. We need her to feel like she has this weight and authority beyond her short years on the planet. She’s one to watch. She’s special.”

Besides telling a well-crafted, brutal, thematically rich story, “Red Queen” is also a farewell to one of the original cast members. In May 2017, shortly after the end of the fourth season, news broke that Isaiah Washington would not be returning as a main character on the show. Washington plays Thelonious Jaha, fallen leader of the space-born Sky People. “I really wanted Jaha’s final episode to be impactful and emotional and special,” Rothenberg says. “I feel like the pairing of Jaha with Octavia was surprising and amazing.”

Another focal point for The 100 is the connection between co-leads Clarke and Bellamy (Bob Morley). When asked if there was added pressure to get the reunion between Bellamy and Clarke (“Bellarke”) correct, Rothenberg laughs. “There’s always pressure to get everything right, so I didn’t feel any more with that,” he says. “It’s a responsibility to two of the most important characters on the show. Obviously, Bellamy thinks Clarke is dead. For that reason alone, we know the reunion will be powerful. But the way this show is, it moves so fast that there’s no time to talk about what it really means. The story is racing on, and the conflict is raging, and they have to keep moving. I feel like it’s a great reunion, of course, complicated by how different they are now.”

The fifth season of The 100 airs on Tuesdays at 9PM on The CW. The latest five episodes are available for free streaming at The CW’s website.