Following their shock discovery, Noah and Rebekah reluctantly return to the lower levels of The Ark. Isolated and apart once more, Noah struggles to remember what happened at the surface and suspects Mother has altered his memory.
But Noah's attempts to unite the workers to rebel are halted when Mother begins The Purge. Her cruel, relentless trials bring Noah to breaking point as he fights to survive when faced by his worst fears.
Forced to accept Mother's terms after a month in Re-Education, Noah finally learns the truth about his people's past that leave him determined to defeat her once and for all.