Deep Inside Silo: Your Guide To Who's Who In Apple TV+'s Dystopian Drama

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Before you journey into the titular Silo of Apple TV+'s upcoming dystopian drama, it couldn't hurt to get a quick, non-spoilery heads-up on who is who within that stark, subterranean society.

Based on Hugh Howey's bestselling trilogy of novels (shop Amazon) and created for television by Justified's Graham Yost, Silo follows the last 10,000 people on Earth as they navigate life in a mile-deep, underground home that protects them from the toxic outside world.

The catch? No one knows when or why the silo was built, and anyone who goes snooping for answers faces fatal consequences.

As a recurring mantra that is read from a text known as The Pact goes:

We do not know why we are here.

We do not know who built the Silo.We do not know why everything else outside the Silo is as it is.We do not know when it will be safe to go outside.

We only know that day is not today.

Rebecca Ferguson (of the Mission: Impossible and Dune franchises) stars as Juliette, an engineer who seeks answers about a murder and subsequently stumbles onto a mystery that goes far deeper than she could have ever imagined. The ensemble cast also boasts Academy Award winner Tim Robbins (Castle Rock), Rashida Jones (Parks and Recreation), Emmy nominee David Oyelowo (Nightingale), Common (Hell on Wheels), Harriet Walter (Succession), Chinaza Uche (Dickinson), Will Patton (Outer Range), Geraldine James (Anne With an E), Iain Glen (Titans) and Avi Nash (The Walking Dead). Here now is TVLine's character guide for Silo (which premieres Friday, May 5 with the first two episodes of 10), followed by the full trailer:

Mayor Jahns is the genial leader of Silo society, though the division known as Judicial does what it can to keep her in check. Jahns' many duties include overseeing the forced exodus of any resident who voices their wish to "go outside." In the early episodes, the Mayor makes a choice that is deemed quite controversial by Judicial, setting in motion a power struggle.

Deputy Marnes dutifully serves Sheriff Holston — and in the series' jarring cold open, which is bit of a flash-forward, Marnes can only look on, helpless, as Holston inexplicably does the unthinkable.

Sheriff Holston is the senior lawman, with several deputies from a variety of Silo levels serving under him. Holston is forced to contend with different conflicts when his wife Allison starts to question well-established Silo tenets, and also when Juliette from engineering leans on him to treat a suspicious death like the murder it (probably) is.

The good news: As the series opens, Allison and her husband, Sheriff Holston, learn that they have been approved to (again) try to conceive a child! That's a big deal in a confined society that demands strict population control.

The bad news? Allison's work in the Silo's IT department draws her into a mystery that threatens to expose a secret, puts her at odds with her lawman husband, and ultimately leads her to make a very difficult choice.

The head of the IT department, Bernard locks horns early on with Allison, over a seemingly benign memo she sent out. Over the course of the early episodes, Bernard will acquire more power and, as such, draw interest from Judicial.

We first lay eyes on Juliette as she makes a dangerous move in order to repair the Silo's generator, which is located within the dreary, lower-most levels. When someone she knows turns up dead, Juliette will lean on Sheriff Holston to get at the truth, no matter the cost — as well as get roped into some detective work of her own.

Martha, who resides in the lower-most levels, is a whiz at repairing things — even the occasional illegal "artifact" (meaning, anything that was created before the Silo and should not have been brought inside). She is also a trusted confidante for Juliette, who at young age turned to Martha for guidance.

As an esteemed physician within the Silo, Dr. Nichols gets to live in the mid-upper levels. So... why does his grown daughter Juliette live in the spartan lower-most levels? And why have father and daughter barely communicated in many years?

Sims is in charge of security for the mysterious Judicial division, and in that role he seems to take great interest in everything that everyone is doing. When a deputy position opens up, Sims will do what he can to advance Judicial's wish to have department member Paul Billings land the job.

Paul Billings is a part of the Judicial department, and works alongside security chief Sims.

Lukas is an IT department employee who captures Juliette's attention by pointing out to her how what appear to be "lights" in the outside sky seem to move, and form shapes. (Here's where you need to know that all library materials were reportedly destroyed in the long-ago rebellion that predated — and ultimately necessitated — the Silo.)

Want scoop on Apple TV+'s Silo, or for any other show? Email InsideLine@tvline.com and your question may be answered via Matt's Inside Line.