There is a delicious problem unfolding in this third season of Silo: every time the series returns to the present, I want to know what is going to happen to Juliette. But every time it leaves the past, I immediately want Daniel and Helen back.

Seven episodes in, it is getting hard to deny it: the past is running circles around the present.

Not because Juliette’s story has stopped being important. The Silo 18 timeline is where we see the consequences of decisions made centuries earlier, and Rebecca Ferguson remains the emotional center of the series. But Daniel Keene and Helen Drew are living through something even more seductive for anyone who has been watching Silo from the beginning: they are watching the mystery being born.

“Radio” finally takes us there. For two seasons, we have wondered who built the silos, why they exist, who created the surveillance system, who decided that memories could be erased and that an artificial intelligence should have the authority to exterminate thousands of people. Now Daniel and Helen are literally entering the space where those answers began.

They finally meet Per Stensen, played by Colin Hanks, one of the richest and most powerful men in the world and someone already associated with artificial intelligence and systems of control. Stensen makes it clear that Daniel, Helen, Charlotte and the others are standing before something enormous, a secret project supposedly designed to “save the world.”

As always in Silo, whenever someone says they are saving humanity, it is probably wise to be suspicious.

Helen hesitates before agreeing to take part precisely because she is a journalist. The promise that she will someday be allowed to tell the story is almost ironic to us, because we already know the world being created there will be built on silence, secrecy, censorship and forgetting.

Stensen also tells a seemingly absurd story about scientists who came close to genetically creating a unicorn, and another billionaire who offered to finance the project simply so that he could later hunt the animal. It sounds like eccentricity, but the anecdote works as a small parable about power. The question is never simply what someone is capable of creating. It is what they decide to do once they discover that they can.

And then comes the image that changes the entire episode.

Daniel and Helen look down at the ground in Georgia and see enormous machines drilling into the earth.

We no longer have to imagine when the project began.

The silos are being built right in front of them.

That is very hard to compete with.

While the past shows us the birth of the system, the present reveals its most perverse function. Robert Sims discovers that Camille has no intention of waiting: Vitamin D+ has already been added to Silo 18’s water supply. We are no longer dealing with the threat of erased memories. The process has begun.

Juliette moves up Lukas and Patrick Kennedy’s mission to Silo 17. They need to find the plans that show where the Safeguard system runs, because Juliette wants to eliminate the possibility of the Algorithm releasing the poison capable of killing the entire population.

Lukas and Kennedy go outside at night and, for a brief moment, Silo even allows itself some beauty. Lukas, who spent his entire life staring at distant points of light without truly understanding what they were, is finally outside looking at the stars.

Peace, naturally, never lasts long in this show.

Near the bodies left behind by the Silo 17 rebellion, the two men begin hearing a strange buzzing sound. The transmission breaks up, Walker hears gunshots over the radio and then there is silence. The Algorithm tells Camille that both men have been “neutralized,” while Camille tells Juliette there was a problem with their suits.

For much of the episode, we are led to believe that Lukas and Kennedy are dead.

They are not.

By the end, Kennedy manages to make radio contact again. He is alive, he has Lukas’ helmet and he confirms that the children in Silo 17 survived as well.

Which immediately raises another question: where is Lukas?

His fate remains unresolved, as does the source of the strange buzzing and the gunshots. Declaring him dead at this point would be premature.

But the most disturbing revelation in “Radio” lies elsewhere.

Bernard returns with Gloria Hildebrandt and brings Juliette Mission’s diary, written during an earlier rebellion. Gloria still remembers Juliette. Juliette, whose own memory has been manipulated, does not remember her.

It is through that diary that we finally understand, much more concretely, what the drug actually does.

Mission records his own mental deterioration while it is happening. People begin to forget. They lose events, references, relationships and pieces of their own biography. The despair caused by this deterioration appears to have driven many of them to suicide.

It is almost impossible to watch without thinking, as a dramatic image, of a kind of state-manufactured Alzheimer’s outbreak. Medically, of course, it is not Alzheimer’s. But emotionally, the horror is similar: remaining alive while the things that hold together your identity, your relationships and your personal history begin to disappear.

Except that in Silo, someone deliberately chose to make that happen.

And perhaps that is one of the most disturbing ideas the series has ever introduced.

The system does not need to convince the population that a rebellion was wrong. It only needs to make them forget that a rebellion ever happened.

There is no need to rewrite history if nobody can remember it.

Without memory, there is no learning. Without learning, there is no history. And without history, every generation can be deceived as though it were the first.

That discovery puts Juliette in a morally uncomfortable position. Without the Silo 17 plans, Teddy suggests simply blowing up Judicial in an attempt to destroy the Safeguard system. The problem is that nobody knows exactly what the consequences would be, and the explosion could kill around a thousand people.

Bernard puts a monstrous piece of arithmetic in front of her: doing nothing could mean even more deaths as the population descends into chaos under the effects of memory loss, while everyone else remains exposed to the drug.

Juliette eventually authorizes the operation.

It is an important moment because she has spent the entire series fighting authorities who justified atrocities by insisting they were necessary to save the silo. Now she is dangerously close to making exactly the same argument.

The explosion is only called off when Kennedy gets back on the radio, and Juliette realizes the Silo 17 mission may still have worked. She gains time before crossing a line she might not have been able to return from.

Meanwhile, Camille and Robert Sims finally stop being merely a marriage in crisis and become representatives of two opposing worldviews. Both believe they are protecting Anthony, but Camille understands survival as obedience to the system, while Robert is beginning to realize that survival without memory may not really be living at all.

And that is what makes the Pez he saves for his son feel even more beautiful — and more frightening.

In a world where a drug can erase even the recognition between mother, father and child, a tiny object can become an anchor. A reminder saying: you knew me before someone ordered you to forget me.

The episode also delivers another important revelation. Knox begins to question the official story of his father’s death and discovers that he may have been right. Everything suggests that his father did not die, and that someone else was buried in his place after he built something for Ed Harwood, who apparently helped fake his death.

We still do not know what he built or where he is, but it is difficult to imagine that this storyline will remain minor. At the same time, Billings and Hank continue investigating Orla’s death and Glenda’s suspicious movements, while Harwood seems increasingly connected to a clandestine network operating alongside the silo’s official structures.

But even with all of that happening in the present, “Radio” ultimately belongs to the past.

Helen and Daniel look down and see an enormous machine drilling into the ground. After three seasons spent trying to go up, escape, discover what lies outside and understand why thousands of people were buried alive inside underground structures, Silo finally shows us the opposite movement.

Someone started digging.

Someone decided that 51 silos would be necessary. Someone developed technology capable of interfering with memory. Someone gave an artificial intelligence enough power to decide when an entire population should forget — or die.

We still do not know exactly what happened to the world to justify all of this. We also do not know whether the silos were truly created simply to survive a catastrophe, or whether their creators somehow played a part in what eventually made the outside world uninhabitable.

But now we know some of the people who were there when that future began to take shape.

That is why the past is working so much better this season.

In the present, Juliette is trying to figure out how to destroy the machine.

In the past, Daniel and Helen are meeting the people who decided to build it.

And every time the series cuts away from them to return to Silo 18, as much as I love Juliette, my reaction has become automatic:

Go back.