The Silo Saga enters its final book set up for success. Wool painted a picture of a bleak future where a dystopian underground society is all that manages to keep humanity on the right side of extinction. Shift then revealed who was behind the building of the silos and their published plan for delivering mankind to a better future; however, it also exposed that the official plan intentionally leaves out that a key decision will eventually made about who will and won't survive. All of this makes for excellent backdrop as the characters from both books converge to determine the ultimate fate of mankind.