Silo Season 3: Vitamin D+ Explained

The following post contains spoilers for "Silo" Season 3, Episode 3.

"Silo" Season 3 is full of mysteries and complications as past and future collide. The underrated Apple TV show about remnants of humanity living in underground silos after some catastrophe destroyed the surface world is compelling, with memorable characters, exquisite production design and a great story full of twists and turns.

After Season 2 changed the status quo and revealed some pretty world-altering information about the silos, Season 3 is not slowing down. Even if it feels like the show hit the reset button by making Rebecca Ferguson's Juliette the mayor of the silo while also taking away her memories, the show is quickly and clearly speeding to a series of high-stakes emergencies, starting with Vitamin D+.

In case you haven't been paying attention, Vitamin D+ are the little pills Juliette has been taking daily since returning to the silo. These are meant to help her recovery after surviving a huge fire upon re-entering the silo at the very end of Season 2. In actuality, these aren't just your normal vitamins. Instead, Vitamin D+ is a memory-suppressing drug. Turns out, Juliette's amnesia is not due to a brain injury, it's not due to trauma. It is an artificial condition done to her via the vitamins by Camille Sims (Alexandria Riley) and the mysterious AI voice known as The Algorithm — which secretly runs the entire silo.

This is already quite nefarious, but in Episode 3 we learn the true plot behind the Vitamin D+, and it is the biggest threat the silo has faced in a century.

At the end of Season 2 we learned that the silos are under constant threat from having their citizens poisoned to death due to the Safeguard Procedure. That threat still looms large over Season 3, but now the Vitamin D+ offers an even more immediate and equally big danger.

Even if peace was achieved after the big rebellion of Season 2 thanks to Juliette returning from the surface, tensions remain. There are those who still believe the outside world is not desolate, but green and alive. And there are those who are doubtful of Juliette's message upon returning that it is not safe to go out. In Episode 3 of this current season, The Algorithm and Camille discuss putting the Vitamin D+ in the water supply of the silo in order to suppress everyone's memory. This would curb unrest and also stop them asking questions about the outside world. It would fix the big picture, sure, but it would mean the silo as we know it would be forever change. Robert (Common) even tells his wife that the vitamin would potentially mean their own son would not recognize them.

The worst part is that this is not a new threat. It's been used before. We know from Season 2 that similar drugs were used after the Salvador Quinn rebellion 140 years earlier, which erased the silo's memory of the entire uprising. It saved the silo from the Safeguard Procedure, sure, but its repercussions can still be felt in the present, as seen in Gloria Hildebrandt (Sophie Thompson) having her memories and mental state severely damaged from years of medication.

Vitamin D+ is not just an urgent plot of the present timeline in "Silo," it is also integral to its past. We see this in Charlotte Keene (Jessica Brown Findlay), who lost her memory after surviving a military operation gone wrong in Iran. In flashbacks, we learn of a controversial doctor whose experiments with memory allow him to essentially rewrite a person's brain, manipulating their memories so they can forget certain things, even aspects of themselves. It is very clear this is the precursor to Vitamin D+.

This is what makes the Juliette amnesia plot so good. It could have been really easy to pull a sitcom-like scenario of Juliette just forgetting her past in order to stall momentum. Instead, her amnesia is intrinsically connected to the overall plot of the season, both past and future. By the time we inevitably see Juliette recover her memories it won't be just a cool thing that can finally move the plot forward, but a huge development that turns the tides.

The fact that even the flashbacks have avoided being just an exposition dump for the creation of the silos is a testament to the writing in "Silo." Having the flashbacks focus on something more small-scale, a mystery of what happened to a man's sister, which still slowly unravels a huge conspiracy, is more compelling while still exploring the origins of things we see play out in the future. Vitamin D+ is very clearly nefarious, and seems a lot bigger than we realize.