The Doctor and Rose find themselves on Justicia—a prison complex that comprises six planets. Seen as trespassers they are both swiftly incarcerated. Rose is locked in a teenage borstal, while the Doctor is trapped in a scientific labour camp. As they each try to free themselves and reach each other, they become aware that something is very wrong with Justicia.
- Adipose Rex: Don Arco, the patriarch of the Blathereen, is large and in charge, both literally and figuratively.
- Badass Decay: In-universe this has happened to the Slitheen family, as they have been surpassed and overtaken by the more ruthless Blathereen family. Though the end of the story implies that the tables may be about to turn again.
- Call-Forward: Rose will mention Justicia when talking to Mickey in "Boom Town."
- Continuity Nod: The Slitheen in this story mention the exploits of Jorcrassa Fel-Fotch Passameer-Day Slitheen, from the TV series episodes "World War Three" and "Aliens of London."
- Killed Offscreen: Unbeknownst to her, one of Rose's cellmates is killed and replaced by a Slitheen midway through the novel.