Roger responds "I was a rat!" to every enquiry about his past, after turning up unannounced on the doorstep of Bob and Joan, a kind-hearted old pair.
Pullman's plays on words provoke the reader to think carefully about the way language is used. "He didn't say I am a rat, he said I was a rat," Bob explains at one point to a befuddled clerk. The text is interspersed with witty front pages from The Daily Scourge and evocatively illustrated by Peter Bailey.