Scraps has been captured by the Government and is given a choice between spying on the Free Citizens or becoming one of the experiments he uncovered in the Department of Advanced Human Research. After being dragged back to the Underground, Flit is determined to find a way to save Scraps. However, her beloved home does not feel like the same place she left months earlier. Whilst Scraps dances on a blade's edge to balance his safety against his loyalties to the Underground and the Free Citizens, Flit has to figure out how to navigate an Underground that is so different to the rebellion she grew up in. Kept apart by circumstance, the pair must work against everything they have ever known to find a way to bring the Government down once and for all.