Victorian London, 1851. Queen Victoria is on the throne and the Great Exhibition is about to open! Lucy Locket lives with her father, the New Mother and the New Baby. They sent away her beloved Nurse and replaced her with a horrid governess. Lucy desperately wants someone to be kind to her, and to have some fun - there's very little of that in her house. Kitty Fisher is a street performer who earns tin for her supper by tumbling. She has always lived on the street and on her wits, with only the kind Gaffer to help her. But now Gaffer is gone, and Kitty is all alone. When Lucy runs away from home, Kitty shows Lucy how to survive. Lucy learns quickly and shows Kitty her own skills - befriending families to get free meals and singing beautiful melodies for the crowds. But the streets of Victorian London are dangerous and soon the girls find themselves under threat from thieves - and even worse.