Ratburger by David Walliams. Ages 7+.
Ratburger (2012) is the story of Zoe, a girl living in genuinely difficult circumstances. Her mum has left, her stepmother Sheila is lazy and unpleasant, and her dad is unemployed and struggling. Zoe finds joy in one thing: a rat she rescues and names Gingersnap, whom she trains to dance.
The villain is Burt, the burger van man, who drives through the estate in a van that plays an ice-cream jingle. His burgers are suspiciously cheap. When Gingersnap goes missing, Zoe discovers the terrible truth about Burt's ingredients and must rescue her rat before it is too late.
The novel handles Zoe's difficult home life with more honesty than most Walliams books. Her resilience and love for Gingersnap are the emotional heart of the story. The ending is warm — Zoe's talent for animal training is recognised and she begins to imagine a better future.