"Shift" is the second book in the Silo series, which began with "Wool." In my opinion, the second book may not be as compelling as the first, but in a way it is more horrifying in its believability. The series ends with "Dust," which is now available for pre-order (coming out August 17 and I'm adding it to my summer reading list asap!).
"Shift" begins in 2039, three centuries before the story of Juliette and Silo 18 --- only 36 years from now. Through the eyes of a young congressman, Donald Keene, we learn how and why the silo system was created. Unwittingly, Keene becomes a party to an act of apocalyptic hubris that poisons Earth and destroys all life --- except the people in the silos.
How Keene begins to understand the scope of this horror, and how he responds, is one of the stories in "Shift." Keene's story intertwines with other plots that answer questions raised in "Wool":
- What was the Great Uprising of Silo 18?
- How did the fall of Silo 17 come about, and how did Jimmy (Solo) survive?
- What was the purpose of Silo 1, and why was it different from the others?
Hugh Howey is a master at weaving all these plot threads together, and drawing rich characters that the reader cares about deeply. I found the timeline a bit confusing, but that is a minor criticism. I eventually drew my own, but a timeline in the book would have been a convenient reference --- especially when the action skips from one century to another.
Donald Keene is one constant through the time-jumping. Cryogenics have been perfected, so Keene is "thawed out" for his shift as the head of Silo 1, and periodically afterward to deal with crises such as the Great Uprising, and Juliette's escape and return to Silo 18. One man, three centuries. Ultimately, Keene (and Howey) leave us with one question: Was this world worth saving to begin with? Were we worth saving?