SPOILER ALERT: Do not read if you have not yet watched the sixth episode of “Snowpiercer” Season 2.

During the first season of TNT’s “Snowpiercer,” Jennifer Connelly spent her days of production crammed on-set with dozens of other performers, all representing the passengers of the titular train, then 1,000 cars long and hurtling around the globe to keep themselves alive amid a climate disaster. The second season, however, sees her much more isolated, as she has ventured out into the snowy tundra to investigate what is happening with the world and with the train, which has now been combined with another to become 1,034 cars long.

The sixth episode of the second season, specifically, provided the Oscar winner with not only a “different rhythm of shooting,” but also a more “authentic” version of the character, she tells Variety.

“The character we spend time with in Episode 6 of Season 2 is a very different woman than the one we’re presented with — or that presents herself that way — in the beginning of Season 1,” Connelly explains. “She hadn’t set out to be the leader on the train; really what she always was was an engineer and just wanted to be in charge of protecting humanity and the science. I think that’s a really interesting journey, and I really enjoyed the process of getting from that character, who has different layers of facades erected and she drops them one by one. But, I think she is still guilty of maintaining that order and doing the things she did to maintain that order; she didn’t change the system, she perpetuated the system, and she’s complicit. And she knows that she did those things and she has to take responsibility. And I think that admission and acknowledgement will forever change her moving forward.”

Although it was through trickery, Connelly’s Melanie Cavill once had command of the train as the lead hospitality representative and a woman with more knowledge of what it could do than anyone else onboard. After a resistance movement by the Tailies, those who lived in the lower amenities back of the train, in the first season, Melanie was humbled. But her life became even more complicated when she learned her daughter Alex (Rowan Blanchard) was not only still alive but under Mr. Wilford’s (Sean Bean) care and tutelage.

Alex being alive was something Connelly felt “should catch the character off-guard,” but thankfully for her process as a performer, it was a plot point that showrunner Graeme Manson shared with Connelly ahead of her character learning that truth.

“Graeme didn’t throw any major curveballs at me. We discussed rather explicitly, ‘What are the things that could be coming?'” she says. What was most important to Connelly was not “the mission that she might go on or the specific interactions she might have or conflicts she might have to deal with or resolve,” but rather, “fundamentally who is she?” She and Manson discussed early on “where she came from and who she is and what her relations are and what her connections are and what is her past with Wilford and how she got here,” and then he “really took me along as he was making [plot] choices,” she shares.

Even after reuniting and trying to rebuild their relationship, Melanie ended up leaving her daughter once again. As she works alone, “many miles” from Snowpiercer, she is doing noble work, but it is not without its own toll. There is the risk of being stranded if the train does not stay on course to pick her up, as well as both physical hunger and an emptiness of the mind. To combat the former, she cooks vermin she miraculously finds in the wall of her station, but the latter is a bit tougher to conquer, and she finds herself having imagined conversations and emotional breakthroughs with everyone from her daughter and Wilford to Andre Layton (Daveed Diggs), and also reminiscing a bit about the events that led to the train taking off without her daughter on it in the first place.

Those memories are depicted through flashback scenes, which Connelly considers “a true account of what happened,” despite the fact that memory is always subjective. “I think it is her subconscious speaking to her; she’s being haunted by her own doubts and insecurities as she’s there, alone on this mission,” she says.

Such moments of showing Melanie fight for her team and their family to be brought aboard and frantically calling to find out where her own family is while the growing mob gets more agitated about the state of the world and the train further exemplify just what she gave up by going out on her new mission now, all of these years later. So, too, does imagining Alex with her in the present, which is what Connelly believes Melanie wants “from the deepest part of herself.”

Unfortunately for Melanie, it may take episodes to reunite in person with her daughter, if she is successful at all. The external challenge she faces when it comes to the changing climate cannot be understated.

For Connelly as an actor, though, shooting scenes in fake snow were not as challenging as they could have been. Although “Snowpiercer” uses some green screen elements to extend the size of and scope of the white landscape when it utilizes wide shots or external shots of the train, Connelly had a lot of practical fake snow in which to “play” on their soundstage.

“Of course the snow is not cold so there are some things that are still in your imagination, but the less work you have to do in your head to be in the place that you are, the easier it is, I think,” she says.

Stepping into the practical environment of the “Snowpiercer” sets also illuminates the need for important conversation and change around tough topics that range from climate change to social justice, says Connelly.

“I always feel like we should learn about things like climate change from scientists; that’s who we should be getting our information from. But one of the things I really liked about the show is it’s a fun, exciting, entertaining spectacle of a show, but it reflects some issues that we’re going through right now,” she explains. “Climate change, obviously, and how we respond to [it, but also] in this season, the division amongst the people on the train feels particularly relevant. Class warfare, arguments for law and order versus science, there are so many things that chime with what we are talking about today and are so pressing in our culture.”

“Snowpiercer” airs Mondays at 9 p.m. on TNT.