Silo Season 3, episode 9 ended with a nuclear blast that transformed the series’ central mystery and left one character’s fate uncertain.

In the episode’s final sequence, Congressman Daniel (Ashley Zukerman) and journalist Helen (Jessica Henwick), who is expecting their first child, visit the silos on the first day civilians are allowed outside. The event is lavish, featuring landscaped entrances and a surprise performance by Peter Gabriel. But the celebration quickly takes a sinister turn.

Why is the mysterious operative Henry (Reed Birney) so determined to keep Daniel and Helen apart? And why does Daniel’s sister Charlotte (Jessica Brown Findlay) stop responding to his messages?

A nuclear blast separates Daniel and Helen

The tension peaks when Daniel and Helen try to find each other. They finally spot one another on the berms surrounding their respective silos, just as a nuclear bomb detonates in the distance. As the blast moves toward them, Daniel is pulled back to Silo 1, while Helen’s fate remains unknown. Since her Pez dispenser eventually turns up in Silo 18, it seems likely that she made it back inside.

The harrowing sequence finally reveals the catastrophe that devastated the area surrounding the silos and sets up a potentially decisive finale. Mashable spoke with Silo showrunner Graham Yost about the episode’s explosive twist, the role of artificial intelligence in creating the Pact, Peter Gabriel’s surprise concert and whether Jimmy (Steve Zahn) could be one of Gabriel’s distant descendants.

How AI created the Pact in Silo

One of the episode’s most surprising details is the revelation that Anna (Morven Christie) and Victor (Matt Craven) used AI to “write” the Pact, the foundational text governing life for Silo residents. Yost explained how the idea reflects the Founders’ attitude toward the people living underground.

Graham Yost: I’ll say, I don’t use AI. But whenever I use Google, I’m using AI now, because I can ask a very specific question like, “How old was FDR’s Secretary of State in 1940?” and up it comes. I don’t have to find out who he was and then look at his life and do the math. So we all use AI now to a degree. I don’t use it that much. I don’t have an AI persona in my life, but a lot of people do. We felt that that was a cool way to explain how something like the Pact could be written. There was one version where there was a team of social scientists who were building this and writing this, and then I was like, “No, let’s just say it’s AI.” It became a joke, which was fun, and the fact that Victor kind of laughed at it, almost like it’s not that important. What’s important is what happens in the bigger story and how it’s acted upon in the people’s lives.

Building the apocalypse in Season 3, episode 9

The episode’s final minutes combine the nuclear explosion with the slow realization that Daniel and Helen are being deliberately separated. Yost discussed what makes an effective apocalypse scene and how the series approached the destruction.

Graham Yost: We had to just kind of do our own thing and set it aside. Fallout starts with a nuclear explosion, and Walton Goggins is there witnessing it. I wrote a movie called Broken Arrow which had an underground nuclear explosion which, for visual effects back in 1996, was pretty awesome, [with] the ground rising up and then sinking down. It’s not new.

The trick for us was Helen and Daniel. That’s what makes it. It’s these two people that we’ve grown to love, and they’re torn apart by it, so that was the story for us.

Interviewer: I’d love to hear more about building that dread around their separation, because as soon as he’s being sent to Silo 1 and she’s being sent to Silo 18, you know it’s over.

Graham Yost: That’s Amber Templemore, our director. There’s some stuff where we are so in sync, and sometimes she’ll do things, [and I’ll worry] “maybe that’s too much.” Then I see it, and I go, “No, we’re doing a television series. We’re trying to be entertaining. We’re trying to do this.” We have to thread this needle between hiding the ball and giving a hint that the ball is going to come rolling down.

Then Atli Örvarsson, our composer, when Daniel is sitting over at Silo 1 and he’s texting Charlotte, Atli does this faint “ding.” It’s just this little sound, it’s just this little thing, and it’s also Ash [Zukerman]’s performance. Now you start to realize, and it builds. There’s Reed Birney [who plays Henry] saying, “Daniel, you have to come with me,” and people telling Helen, “You can’t go up on [the berm].” You just know something bad is going to happen, and guess what? Something bad happens! It’s a build in the script, it’s a build in the design, it’s a build by Amber.

Was the bombing part of Per Stensen’s plan?

The attack takes place on the first day that civilians are permitted outside the silos, making its timing especially suspicious. The episode also shows Per Stensen receiving a message as he leaves the stage, raising questions about what led to the bombing and whether it was part of his larger plan.

Interviewer: I do have to say, this attack is very suspiciously timed to the first day the silos are open to civilians.

Graham Yost: [laughs] What? That’s weird. So weird.

Graham Yost: I don’t know. We didn’t think about that!

Interviewer: But it seems pretty obvious that something is going on. We see Per Stensen get a message as he leaves the stage. I’m curious, will we find out more about the actual events leading up to the bombing? Was it a part of his master plan?

Graham Yost: [laughs] You’ll have to pay to find that out.

Peter Gabriel’s surprise appearance in Silo

The episode also features a surprise appearance by Peter Gabriel, creating a connection to the use of his song “Come Talk to Me” at the end of Season 3, episode 1. Gabriel and his family are revealed to be living in Silo 17, prompting speculation that Jimmy or other children in the silo could be among his descendants.

Interviewer: I also loved the Peter Gabriel cameo. It feels like a full circle moment after using “Come Talk to Me” at the end of Season 3, episode 1. We learn that he and his family are living in Silo 17, so there’s a chance Jimmy or the other kids are Peter Gabriel descendants. Can you canonically confirm or deny?

Graham Yost: I can canonically confirm. There’s a non-zero chance. We did not actually walk that through. There are some family bloodlines that we have discussed. But the Gabriel thing goes back to Season 2, when Solo/Jimmy is trying to lure Juliette (Rebecca Ferguson) back to the vault door because he wants to talk to her about something. He plays “Red Rain” by Peter Gabriel, so that music exists in Silo 17. That’s why we knew he had to go into 17.

[Gabriel and I] got to know each other through the show. I’d approached him about something in Season 1, and it didn’t work out. But we connected, and we’d been talking about other things. He ended up watching the show with his family, and they loved it. So I said, “Would you do this thing?” He said, “Yeah, I’m free. Can I bring my son, and can he can he bring his girlfriend?” I said, “Sure.” So that’s his son and his son’s girlfriend at the side of the stage.

Will Smith, the showrunner on Slow Horses, he and I bonded over Peter Gabriel back in the early days of Slow Horses. So I told him, “Hey, you’ve got to come to set on this day.” He’d been one other day because it’s a fun set to visit, but this was outside. I didn’t tell him [about Peter Gabriel]. We were walking from his car to set, and Peter’s coming the other way to go to his trailer, and [Smith] says, “Is that him?” I said, “Yeah.” He said, “Fuck me.” So we got to hang out with Peter and his son and his son’s girlfriend, just making a TV show. That was a fun day.

Interviewer: That’s delightful. There’s nothing like a Peter Gabriel performance before the end of the world.

Graham Yost: And the song, “Here Comes the Flood.” Reed Birney said to me on the day, “it’s a little on the nose, isn’t it?” I said, “Reed, we’re doing a TV show. It is.” Hopefully the audience doesn’t realize when Peter’s singing “say goodbye to flesh and blood” that in fact we’re going to see a nuclear weapon go off later.

The interview above was edited for length and clarity.

Silo Season 3 is now streaming on Apple TV. The finale premieres Sept. 4.

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