At its core, the Silo series is a meditation on . Howey explores how history can be erased and rewritten to keep a population compliant. The Silo is a pressure cooker of class struggle, where those in the "Down Deep" provide the labor while those at the top hold the secrets.
The most terrifying aspect of this society is the "Cleaning." Those who express a desire to leave or break the law are sent outside to clean the external sensors that provide the Silo's only view of the world. They always clean, and they always die within minutes. The Trilogy Breakdown hugh howey silo series