Silo season 3 opened up a whole new timeline this year with the Before Times, telling the story of the world as it was centuries before the silos sealed. Running through it were two of the best new characters the show has introduced across its entire run: Daniel Keene and Helen Drew. Ashley Zukerman and Jessica Henwick were phenomenal in their roles and I think a lot of people ended up more invested in their story than in anything happening in the present-day silo.
Alongside them though, the show also introduced the eccentric Per Stensen. He is dubbed the world's richest man, and we eventually learn that he is the person who envisioned and funded the whole silo project. Colin Hanks played him with this odd mix of energy that is funny one second and unsettling the next.
Though we don't see the character until episode 7, the show had actually been seeding him since the beginning of the season. The Heidi Stensen Clinic we learn Charlotte Keene was being treated at after her F-35 squadron crashed is actually named after his mother! He had notably been involved in one of the Before Times' final mysteries before the nuclear explosion went off in the penultimate episode, which makes it strange that the season 3 finale, "Troy," skipped over him completely.
Per Stensen looks horrified in the glimpse we get of him in the Silo season 4 teaser
While we weren't given the exact whereabouts of Stensen in the final episode, the season 4 teaser confirms we will see more of the character, at least in the Before Times story. In one shot of the teaser, Per Stensen is shown standing in front of a wall of television screens, multiple news channels all running at once, and the look on his face seems like pure terror.
From the very moment he had been introduced in episode 7, Stensen has looked like absolutely nothing could rattle him. So, that expression in the teaser is totally worth paying attention to. I think that shot is possibly the moment he decides to put his plan for the silos into motion.
A trailer breakdown from Show Snob noted that the screens appear to be showing reports of unusual incidents, specifically blue whales washing ashore, which could point to early environmental fallout from nanotech deployment. Whatever is on those screens, Stensen's face tells us it means a great deal to him.
Per Stensen's biggest fear is also what made him as powerful
By episode 8 "Gray Goo," the Before Times picture had pretty much come into focus. We learned that Stensen made his fortune in nanotechnology and understood better than anyone what a nanoweapon could do. He also knew it was only a matter of time before an enemy government worked out that building one was far cheaper than a nuclear warhead.
He was right in that Iran deployed a nanoweapon on the Dulles Tech Corridor (the dirty bomb), targeting U.S. AI and nano research. Charlotte Keene's air mission was essentially a sacrificial distraction to gauge how advanced Iran's nano program had become.
During the dinner scene in that episode, Stensen goes on to explain to Daniel and Helen what Charlotte had actually flown into. He shares in detail the full range of existential threats he is trying to prepare against and is clear about which one scares him most.
"The one that is most dangerous is also the reason why I'm the richest man in history," he said at that table. "Nanotechnology. Not just because it's invisible, but because I knew that an enemy government would soon realize that a nanoweapon was a hell of a lot cheaper to build than a nuclear one."
Stensen had been impersonating Charlotte Keene in text messages to Daniel
In episode 9 "Farewell," we see Daniel at the silo launch event trying to text Charlotte, who is notably absent. He sends her the opening line of a joke the two of them share, a running sibling thing, and the reply he gets back is completely wrong. The tone is clearly off and Daniel notices immediately.
What Daniel does not see but the audience does is that Stensen is standing near the podium holding Charlotte's phone, answering those texts impersonating her. But why, and where exactly was Charlotte at the time?
Our guess is, Charlotte had already been moved into Silo 1 before the nuclear explosion went off, given we see her as Susan all these centuries later in the finale. Perhaps she found out about the impending end-of-the-world Stensen and Thurman were about to trigger, and because she is "important" to Thurman's daughter Anna (as Rosalind herself puts it in the finale) they made sure she wasn't able to communicate with Daniel and was taken underground before it happened.
What Stensen was doing with her phone while standing at a public ceremony impersonating her to her own brother, is a question we would love answered in season 4. The most straightforward reading is that he was managing Daniel, keeping him calm and keeping him in position to be guided toward Silo 1's entrance when the moment came.
So, where could Per Stensen be now?
Season 3's finale skipped past Stensen entirely. We saw the horror of exactly what happened to Silo 17 and how Daniel had been memory conditioned to his Troy persona, Rosalind Thurman posing as the Director, and Henry as the head of internal security woken in shifts, but Stensen's fate — whether he made it underground, which silo he's in, and whether he is still alive three centuries later — was left completely open.
The reasonable assumption is that he is in Silo 1. It is the only logical place for the man who funded and built the entire project. Silo 1 is where the founders went, cycling in and out of cryogenic suspension as needed. Victor Crnkovich ended up there, essentially becoming the voice of the Algorithm (or I think one of the voices, given the silo's residents are woken in shifts).
Notably, there is no Per Stensen in the books. The character was invented entirely for the show. So, Hugh Howey's novels offer no roadmap for where he goes. The writers have complete freedom with him, which also means complete responsibility for how his story ends.
In season 4, we need quite a few questions about Stensen answered, starting with whether he made it into a silo. And what exactly was he doing with Charlotte's phone? What was on those screens in the teaser and where does that moment sits in the Before Times timeline? Will Daniel, now Troy, with his memories slowly surfacing, come face to face with the man who tried to recruit him three centuries ago? And most fundamentally, what does Stensen actually think happened? He built the silos to give humanity a second chance. But does he know that now? Does he even remember who he was?
Silo season 4 premieres July 9, 2027 on Apple TV.
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