'Silo' Season 3, episode 2's ending explained: What is Vitamin D+?

Silo loves ending with an ominous shot of something mysterious, and Season 3, episode 2 is absolutely no exception.

But what are those big barrels of the troublingly named "Vitamin D+" being pushed up the central staircase? And what will they mean for the silo's residents? Let's break down what we know.

What happens at the end of Silo Season 3, episode 2?

Camille (Alexandria Riley), thinking she's managed to smooth out the growing issues with Juliette (Rebecca Ferguson), heads back to the Vault for a chat with the mysterious Algorithm.

But based on what the voice says to her, it sounds like the problems for Silo 18 are only just beginning.

"After her return, Juliette's survival was...unwelcome. But the numbers indicated it was tolerable. Perhaps even beneficial," says the voice, before bringing up a graph on the screen. "The blue line represents the calming value in the silo of having Juliette Nichols as mayor. The red line is the risk she poses if the memory protocol is not successful. If those lines cross, Juliette Nichols will have outlived her usefulness. The problem, of course, is that a sudden removal of Juliette could be catastrophically destabilising. We can only hope that the introduction of the vitamin compound into the water supply happens before that becomes necessary."

Vitamin compound? Water supply? It's not looking good, and nor does the sight of silo workers shoving large "Vitamn D+" barrels up the winding staircase in the episode's closing shots.

But what exactly is the compound, and how will it affect the silo's population?

What is Vitamin D+?

The answer seems pretty clear, and it links back to 1) What's been happening this season with Juliette, and 2) Another conversation between Camille and the Algorithm at the start of the episode, where Camille is complaining about how long it's taking Juliette to forget what happened to her.

"We have 352 years of data that demonstrates the protocol is effective most of the time, when implemented correctly," says the robotic voice in response. "Six silos have successfully undergone full resets, including your own 140 years ago, and there have been individuals targeted along the way."

So, we know Juliette is being given a drug that affects her memory. But the talk of a "full reset" suggests this strategy has been implemented on a much wider scale in the past.

Those "Vitamin D+" barrels being rolled up the stairs? Most probably the same memory-wiping medication being given to Juliette. Only this time, the target is everybody in Silo 18. Another "full reset" is in the works.

Silo Season 3 is streaming now on Apple TV, with new episodes dropping every Friday.