The following contains spoilers for the “Silo” season 2 finale, “Into the Fire.”

Apple TV+ is home to many of the best sci-fi shows currently on the airwaves. Whether it’s the alternate history glee of “For All Mankind” or the joy of watching Lee Pace as an immortal emperor fighting a bunch of assassins while completely naked in the epic “Foundation” or the (relatively) more grounded “Severance,” there’s something for every kind of sci-fi fan on Apple TV+.

Now, one of the streamer’s best sci-fi shows (and shows overall, for that matter) has finished its second season — “Silo.” Created by Graham Yost and based on the book series of the same name by Hugh Howey, “Silo” takes place in a dystopian future where the remnants of humanity live inside a giant underground silo hundreds of stories tall. Narratively, the show centers on Juliette Nichols (Rebecca Ferguson), an engineer who becomes engulfed in a huge conspiracy as she slowly unravels the many mysteries of the silo (aka Silo 18). It’s a phenomenal series full of intrigue and exquisite world-building, with the titular silo feeling like a lived-in place.

The idea of a show where the remnants of humanity live surrounded by walls and the truth of their world and the origin of their cities is a secret the protagonists have to uncover (in a basement, no less) also makes “Silo” a good accidental live-action “Attack on Titan” series.

With “Silo” having been renewed for both a third and fourth season (with season 4 set to serve as its last), there’s still a lot of story left to cover if the show intends to fully adapt the rest of Howey’s novels. This is especially true after season 2 ramped up the mysteries, introducing a big rebellion plot, a new silo (aka Silo 17), an AI, and even a trip back in time. In short, a lot happened this past season, and the season 2 finale, in particular, offers some answers while raising a whole lot more questions.

Whether you’re confused about the latest twists and turns of “Silo,” or you simply want to relive the shocks, the thrills, and the surprises, we’ve got you covered.

Arguably the biggest reveal of the season 2 finale, titled “Into the Fire,” involves what Lukas Kyle (Avi Nash) found in the tunnel at the very bottom of the silo. This is the same tunnel that Juliette’s boyfriend George Wilkins was investigating before he died — a place that only he, Salvador Quinn, and the late Judge Mary Meadows had reached before Lukas. As it turns out, the tunnel leads to a door safely guarded by the same entity behind the Legacy that’s in the secret IT vault.

The voice tells Lukas about the Safeguard Procedure, a contingency plan that allows this unseen voice to literally kill every single person in the silo with a vent. This changes everything for the show and opens up a whole new can of worms. Who exactly is in charge of deciding when to push the button? Under what circumstances would it happen? Given these are supposed to be the last people on Earth, why would you want to annihilate any chance at repopulating the planet? (Unless this is actually a Vault-Tec situation where the silos are but twisted experiments à la “Fallout.”)

Meanwhile, over in Silo 17, Steve Zahn’s Solo (aka Jimmy, aka the best character on TV) suddenly remembers that his parents knew about the procedure involving a vent full of poison and explains the situation to Juliette. He also informs her the people from Silo 17 who went outside didn’t die, at least not at first. In fact, his parents not only found a way to stop the poisonous vent and make the silo safe in the long run, but they even made it safe to go outside.

That’s right. Outside. This is groundbreaking. Does this mean that the outside world isn’t toxic? How would poison from inside the silo that is technically not used until a critical moment impact whether it’s safe to go outside? Unless there’s some sort of technological aspect to the virus, i.e. something that kills the person only after they go outside (or when the Safeguard Procedure gets activated). That’ll have to remain a mystery for now. Until then, this new information complicates everything and puts the entire history of Silo 18 in a different context. It seems the silo’s residents are not survivors after all; they’re actually prisoners or, if you will, ants on a farm sitting on a bomb someone can detonate on a whim.

The other major story thread that gets mostly resolved in the season 2 finale concerns the traitor in Mechanical and the larger Silo 18 rebellion. Turns out, the rebels all knew Martha (Harriet Walter) was snitching for Bernard (Tim Robbins) because she literally told them the first chance she got using hand signals they use to communicate down in Mechanical. (Of course Bernard was arrogant enough to assume the rebels would never think of a way to communicate with each other non-verbally.)

With new reason to hope that Juliette might still be alive, Mechanical prepares for war, finally making good on all their threats to blow up the engine. Except, that’s really just a ruse to lure Bernard into sending all of Judicial’s raiders down to the lowest levels while everyone in Mechanical storms the stairs and reaches the top — then blow up the stairs. You read that right: a good chunk of the stairs are now gone in the lower levels, trapping all the raiders down there.

Now, this has huge repercussions for the future of the show. Stairs like that will take quite a long time to get rebuilt, so what exactly is going to happen to Mechanical and the engine itself? What about the people caught in the middle levels who can’t move up or down? Whatever happens next season, there will be major shakedowns in Silo 18. Sure, Sheriff Billings (Chinaza Uche) still has all his deputies on his side, so they can maintain some sort of order, but with so much of the population from Mechanical now trapped in the upper levels, they’re going to have to deal with their own “Snowpiercer”-style situation in the silo of having too many people and not enough space.

It doesn’t help that Bernard ups and quits his job the moment he learns of the Safeguard Procedure, giving the keys to the vault and the title of head of IT to Robert Sims (Common). Naturally, though, Robert is yet again thwarted from finally getting what he wants. Instead, the moment he walks into the vault with his family, the voice of Legacy acknowledges him and sends him away, only willing to talk to his wife Camille (Alexandria Riley), who seems to be the new person in charge of things.

Just as the rebels are about to burst through the door and die on their way outside, they spot Juliette walking back from that fateful hill. She holds up a sign to the outdoor camera saying it is not safe to go outside, and runs into Bernard on his way out and convinces him to stay and stop the Safeguard Procedure from happening.

Except, it turns out the entrance to the silo is also an incinerator, and we cut to black just as the room Juliette is in gets engulfed in flames. Now, it is highly unlikely that Juliette is actually dead because she is wearing a firefighter suit — and why would any show waste Rebecca Ferguson like that? The better question is what happens when she reaches the people of Silo 18, because now that she’s back, they’re going to have many questions about how she survived without food or water out in the wasteland. Will she tell them everything about Silo 17, the Legacy, the outside world, and the poison? It’s likely Bernard is dead and with him dies any knowledge about The Order and the rules of the silo, so all bets are off in terms of what they can or should do — as long as they fix the poisonous vent first.

Then there’s the epilogue, the most fascinating part of the episode. After Juliette’s fiery end, we cut to Washington, D.C. in what looks like our present, one free of silos. Turns out, a dirty bomb was detonated in D.C. in the recent past, and there is enough radioactivity that people now have to get checked before entering restaurants. We meet a politician and a reporter on a date (except, they don’t call them dates in this timeline unless you’re 95), and the season ends with the woman opening a gift, something small the politician bought at a convenience store on the way — the Pez dispenser we saw all the way back in the first season, a relic that endures to Juliette’s day.

It is clear we’re going to see the origin of the silos, since it’s unlikely that’s a random Pez, and even more unlikely that the Pez would somehow be passed down from that woman to future generations until they enter the silo. No, that reporter is definitely amongst the citizens of Silo 18. The question is, how long until we get back to Juliette and the others?

The first two seasons of “Silo” are now streaming on Apple TV+.