~2049-2052 TheoryMajor
The silos are constructed
In Hugh Howey's trilogy, 51 silos (50 populated plus a command silo) are built before the surface becomes uninhabitable. The show has not fixed these dates on screen.
Silo Universe
Timeline
Every reveal from the Before Times to the Season 2 airlock cliffhanger. Book-sourced history is flagged as such.
The Before Times
The world above, ~300 years ago - and how the silos came to be.
S3 · Before Times TheoryMajor
Daniel Keene and Helen Drew uncover the conspiracy
A congressman and a journalist investigate a dirty-bomb attack and are pulled into the plan behind the silos - the show's human-engineered origin, told in Season 3's Before Times track.
Silo history
The Rebellion, the erased records, and the fall of Silo 17.
Year 0 AR TheoryMajor
The Rebellion is crushed; the records are erased
In the novels, Salvador Quinn, then Head of IT, destroys the silo's history - servers wiped, books burned - and blames the rebels. The show surfaces a version of this through the Book of Quinn.
Decades ago CanonMajor
Silo 17 goes outside and dies
A failed uprising empties Silo 17 - its people walk out and die, leaving only a boy, Solo, sealed in the IT vault.
Season 1 · 2023
Holston cleans; Juliette walks over the hill and lives.
S1E1 · May 5, 2023 CanonMajor
Sheriff Holston asks to go outside
After Allison's death, Holston cleans and dies over the hill, leaving Juliette his badge and the first thread of the mystery.
S1E6 · The Relic CanonMajor
The forbidden hard drive surfaces
George Wilkins's hidden drive of pre-Rebellion data becomes the engine of Juliette's investigation.
S1E10 · Outside CanonMajor
Juliette refuses to clean and survives
Sent to clean, Juliette does not wipe the lens, walks over the hill, and lives - shattering the central lie that the outside kills instantly.
Season 2 · 2024-25
Silo 17, the Book of Quinn, and the Safeguard.
S2E3 · Solo CanonMajor
Juliette reaches the dead Silo 17
She finds a flooded ruin and its lone survivor, Solo - a warning of what Silo 18 could become.
S2E8 · The Book of Quinn CanonMajor
Salvador Quinn's note becomes central
Quinn's message reframes the tunnel, the Order, the Legacy and the Safeguard, and ties Meadows and Lukas into the same chain.
S2E9 · The Safeguard CanonMajor
The Safeguard is revealed
The silo's ultimate fail-safe surfaces - the machinery built to reset or end a silo that learns too much.
S2E10 · Into the Fire CanonMajor
Season 2 finale: rebellion and an airlock cliffhanger
Juliette returns to Silo 18 amid open rebellion; the finale ends on a fire/airlock cliffhanger and a pre-silo flashback that hints at the origin.
Season 3 · 2026
Now airing weekly. The Before Times, on screen.
S3E1 · July 3, 2026 CanonMajor
Mayor Juliette wakes with no memory of the truth
Season 3 opens with Juliette installed as Silo 18's mayor and amnesiac after the incinerator fire - fed daily "reminders" that the silo is at peace because she came back. She realises the gaps are not an accident: someone wants her to forget what she found outside.
S3E1 · July 3, 2026 CanonMajor
Bernard is dead - and Robert made sure of it
The premiere confirms Bernard did not survive: burnt and poisoned in the airlock, his body taken to the incinerator by Robert, who personally ensured nothing was left. How much of the killing was the poison and how much was Robert is left pointedly open.
S3E1 · July 3, 2026 CanonMajor
The Before Times timeline opens
A second timeline set ~300 years earlier follows congressman Daniel Keene and journalist Helen Drew, whose investigation into a looming catastrophe suggests the silos were a deliberate plan rather than a desperate response to disaster.
S3 · through Sep 4 Theory
Ten episodes, one per Friday
Season 3 runs weekly through September 4, 2026, cross-cutting Juliette's present with the Before Times as the origin of the silos comes into view.