If you’ve already watched Extinction, you know that Netflix’s new original sci-fi movie hinges on a pretty big twist. The entire third act leading up to the ending subverts your expectations to the point that you may be a little confused. Rewatching Extinction is one way to clear up those plot details, but why not let director Ben Young and lead actor Michael Peña explain it to you?

Inverse spoke with both Young and Peña in interviews leading up to Extinction’s release. Here are all the spoiler-filled quotes we couldn’t share ahead of time to help you make sense of the ending and everything that comes before it.

Warning: Brain-melting Extinction spoilers beyond this point.

extinction spoilers ending explained

Recapping the plot

If you need a quick primer, here’s the basic plot of Extinction. In a near-distant future, humans invent artificially intelligent robots called Synthetics that look identical to humans. Initially, they’re used for menial labor, and in flashbacks with see both Peña and Lizzy Caplan’s characters working as cleaners in some sort of office.

It doesn’t take long for a growing group of concerned humans to call for the destruction of all Synthetics, worrying that the robots will rise up against their masters. But when the military tries to wipe them out, the robots fight back. They defeat humanity, forcing any surviving humans to flee the planet entirely. At this point, most Synthetics voluntarily wipe their memories and begin blissful new lives as humans on Earth, while a few robots (including Mike Colter’s character) retain their memories and prepare for the inevitable return of humanity.

That’s where the movie begins. Peña’s character attempt to live a normal life but keeps seeing flashbacks of the initial war against humans, which he wrongfully assumes are visions of the future. Then, when the humans do show up to reclaim Earth, the Synthetics retreat to specially designed safehouse hidden beneath a mountain and begin to prepare for the next inevitable attack. Credits role. The end.

extinction spoilers ending explained

Designing the “aliens”

When the humans first attack they have to look like aliens. After all, you don’t learn who they really are until Peña overpowers one and it turns out to be a frightened young Israel Broussard. To pull that off, director Ben Young spent a lot of time thinking about exactly how the attacking humans should be dressed.

“It was very difficult coming up with the costumes,” he told Inverse, explaining that the uniforms we see are designed to show their age. “We see a hint of what the costumes may have looked like when they were brand new. They’ve been conditioned and weathered to hell. We began by designing them looking more traditional and then aged them down.”

It makes sense. If humanity was forced to flee Earth, then they probably weren’t able to bring much with them. So whatever sort of gear they left with is probably what you’re seeing now. The fact that it also looks particularly alien is just a nice perk.

extinction spoilers ending explained

Acting like a robot

Taking on the part of a robot that thinks it’s human might not be the most original role, but it’s still a tough one. In Extinction, Michael Peña and Lizzy Caplan both had to act human enough not to spoil the twist early on, but also robotic enough that the film would make sense when watched a second time.

“For me, what I tried to do is portray him as very confused and not a lot of energy,” Peña said. “Almost a lot of preconceived notions of how people would react. Like, I should be reacting like this. I should be reacting in this manner. And some people that haven’t seen it or whatever. They might think like wow. This guy’s really boring. They might not understand it yet, but it was a very deliberate thing in order to work out. It was tough because as an actor you want to live in every scene but sometimes you just can’t.”

Peña said he was particularly impressed with Caplan’s performance and the way she spoke with a distinct, almost robotic rhythm that you might not notice if you aren’t listening for it. Pay extra attention to her acting in one particular scene early on where she’s lying in bed telling a story to their two daughters.

“You clock that as an actor afterward,” Peña said, “and you’re like wow she had this whole thing planned out.”

extinction spoilers ending explained

What comes next?

There’s no guarantee Extinction will ever get a sequel, but Young already knows what he would do if given a second chance to revisit this world.

“If we go down that path I’d love to hear the human perspective of what went on,” the director said, quickly spinning a sequel out of thin air. “After they reclaim the planet how would they hunt down the Synthetics?”

Considering that Extinction ends on a note of cautious hope for the Synthetics, that’s a pretty grim plotline for Peña and Caplan’s characters. But, hey, at least it would give Broussard a chance to come into his own as a human soldier with a soft spot for the robots he’s supposed to be killing.

Extinction is streaming now on Netflix.