Cosima Unfortunate has spent all her life at the Home for Unfortunate Girls - a school where any disabled children, or children deemed different, are sent, whether their families want it or not. It is there that she meets her friends - Pearl, Mary and Diya - and they start to practise mini heists involving the theft of cakes, biscuits and other sweet goodies. But when Cos finds out that Lord Francis Fitzroy, the explorer behind the Empire Exhibition, is planning to adopt them, she and her friends plot the biggest heist of their life.