Season one covers the first 30 chapters of the book "Wool," which has 82 chapters total. Season two covers the remaining chapters of the first book, also introducing characters from the second book, "Shift."
Based on the books of Hugh Howey, who was an early adopter of self-publishing. Howey found success using the then-new Amazon Kindle format and managed to generate a sustainable income from his self-published books.
The three books in the Silo trilogy by Hugh Howey are called "Wool" (2011), "Shift" (2012), and "Dust" (2013). The title "Wool" refers to the material of the cloth that those being sent outside are given to clean.
Apple TV+ ordered season two on 14 June 2023.
The helmet for the suits in which those who are sent outside to clean are almost identical to the helmets used on the spacesuits in "2001: A Space Odyssey."