Reading Shift is like finding all the keys to the locked doors in Wool. Howey keeps the pace moving and I was pulled into the backstory of the reason for the Silos and the reasons Silo 1 was different than the rest. There is a stand alone description of a silo (maybe 18's?) first uprising as a character named Mission finds himself fighting for his life without a clue as to what is going on. I have read in other reviews that readers feel Howey is short on character building and that is true but I think this series is one where it is the events that matter. The characters are just pawns by the wayside. I do have one serious problem with the idea of the Silo's. Built in 2052 and all the plumbing, power sources and especially the "I.T." resources have been successfully maintained for hundreds of years. Amazing. I know it's Sci Fi but I have a hard time imagining any system working that well for that long, in that many places even when the penalty for questioning or failure or refusal to cooperate is death. That said, The Shift series was as good in it's own way as Wool and Dust is next.