After tonight, nothing will ever be the same on The 100.

Sure, The CW’s post-apocalyptic drama has served up dramatic twists before. But believe me when I say that tonight’s episode, “Thirteen,” will change everything about the series, both going forward and in terms of what we’ve already seen in two and a half seasons. It’s not going to rewrite history, but it is going to explain why everything we have seen has led to this moment.

If that sounds incredibly vague to you, then I’m doing my job! Because you definitely don’t want to be spoiled for these game-changing reveals. Some of them take place in flashbacks, as The 100 travels 97 years into the past to show the ultimate origin story of how the world of the series came to be. But some of them take place in the present, in Polis. (The, ahem, situation in Arkadia unfortunately gets put on pause this week, as there was too much story to tell with the flashbacks and Polis to fit in anything more. But you won’t even realize that the entire Arkadia storyline is absent because you’ll be too focused on what goes down in the episode!)

The show’s creator Jason Rothenberg tells Nerdist that he’s been eagerly waiting for the chance to get to tell the flashback story of the 13th space station, Polaris, that never made it to the Ark.

“I definitely knew that I was going to tell that story eventually,” Rothenberg says. “I wanted to tell the story of what happened back at the beginning and what is the origin story of the Ark. That’s what this flashback story does.”

Eagle-eyed viewers know that the story of the destruction of Polaris was actually teased way back in season one, before we learned that Polaris eventually became Polis, the Grounder capitol.

“When we talked about Unity Day, Finn [Thomas McDonell] said that the Unity Day story is a myth. It’s bullshit. It’s a lie,” Rothenberg says. “Clarke and he have this conversation about the 13th station and blowing it out of the sky and how that’s not the kind of thing we talk about at parties. I love the idea of answering that question finally. It’s part of our mythology and now we get to see how it really happened.”

But the full story of why the other 12 stations shot Polaris out of the sky has more to it than just inspiring the feeling of unity by joining the Ark.

“We very rarely will go straight flashback without having there be a real purpose behind it, like a twist or something we didn’t anticipate—a new wrinkle in that story,” Rothenberg teases. “If you think about the times we’ve flashed back previously, there was always a twist. This one has several, huge twists.”

Will The 100 continue to flash back to the Polaris story after this episode?

“I don’t want to say definitively yes or no to whether or not we’re flashing back more this season,” Rothenberg says after a pause. “What I will say is I think that the end of this episode, the dots are there to be connected to how the world is what it is right now.”

There’s one twist in particular at the very end of the episode that is sure to break Twitter tonight and inspire a ton of theories going forward.

“That’s what we hope,” Rothenberg says with a laugh. “All the seeds [about this twist] were there all along, so this mind-blowing reveal was right in front of your face the whole time. The best twists are like that. I hope that it works. I’m very proud of that. I think we stuck that landing but we’ll see what the audience thinks.”

Rothenberg hopes that fans agree with him, since the twist is one of his favorite moments of the series.

“I’m most excited for everyone to see the big reveal at the end of the episode,” Rothenberg says. “I’m also excited for them to see the origin story of the show. We see how the Ark was created. We see the apocalypse and we understand why it happened. We see that it’s all connected to the bigger story that we’re telling. I’m excited for all the pieces to come together.”

What do you think will happen in this big, game-changing twist? Tweet me your theories at @SydneyBucksbaum, and make sure to check Nerdist after the episode airs for scoop from Rothenberg on what it all means for the show going forward!

The 100 airs Thursdays at 9 p.m. on The CW.

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Images: The CW