The Prologue is a conversation between Donald, an architect from Silo 1, and Lukas, the head of IT in Silo 18. Lukas confirms that he has been reading encyclopedias, which feel like gibberish. The Prologue ends with Lukas’s ominous prediction that things will not end well.

In the silo’s mechanical department, Mayor Juliette Nichols uses a digger to attempt to break through the concrete wall of Silo 18, to the disapproval of the miners. She has only recently learned that other silos exist and wants to reach Silo 17, which is almost entirely empty except for a few survivors. She breaks down the wall just as the excavator experiences mechanical issues.

On the other side of the wall is a bizarre, ancient machine. Juliette leaves Dawson, the third-shift foreman, to manage expanding the dig and helps the head of Mechanical, Shirly, clean the generator. Their interactions are tense because Juliette’s rebellions have recently led to the death of Shirly’s husband. Nevertheless, breaking through the wall has given the miners new energy and hope.