Wool is the discovery of the prison. This is the confession of the men who built it.
Shift jumps back decades before the silos were sealed and explains how it happened, which is the most uncomfortable stretch of the trilogy, because the answer turns out to be committees and reasonable-sounding decisions rather than villainy.
It gets called the least interesting of the three. I think it is the most useful. Reading the design intent after living inside the result changes how book one sits.
Read March 2025.