Holston is the sheriff of the silo, a 144-floor underground community of humans. They have lived there for generations since an unknown event caused the air above ground to become toxic to humans. Wool opens with Holston climbing the spiral staircase to the top floor, reflecting on how the spiral staircase has been worn down by centuries of humans: “Each life might wear away a single layer, even as the silo wore away that life” (3). Holston reflects that the year his wife Allison died, the couple had won the lottery that would have allowed them to have a child, but they were not able to conceive.

On the top floor of the silo, there is a cafeteria with a projection on the wall of the outside world. The scene shows a hill with brown, lifeless vegetation, beyond which is “the top of a familiar and rotting skyline” (5).

Holston goes to his office, where Deputy Marnes greets him. To Marnes’s confusion, Holston puts himself in the holding cell from which prisoners are sent to “cleaning,” the silo’s form of execution; the condemned go out of the silo to clean the cameras that show the view of the outside world before succumbing to the toxic gases.