The book is the story of a child criminal released into society as an adult, taking its title from the court practice of concealing the identity of child defendants and child killers.
The book and film share several similarities with the notorious murder of James Bulger at the hands of two ten-year-old boys in 1993. Jonathan Trigell has said that the character of Jack/Eric is based on a childhood friend of his who had struggled with life outside prison after serving a lengthy sentence, although not for murder. Trigell has also said the book was influenced by the media frenzy around the Bulger murderer's release.