It’s six months since Rob’s mum died. His dad won’t talk about her at all. So Rob fills a suitcase in his mind with all his forbidden thoughts – the rash on his legs, the bullies at school – and keeps it tight shut. But when he finds a caged tiger deep in the woods, his whole life begins to change. That same day he meets Sistine Bailey, another outsider who’s bullied at school. She says they must set the tiger free – and when Rob imagines the tiger rising out of its cage, his suitcase begins to open.