It's 1899 and a young girl is abandoned in London by her feckless family. She finds lodging and work assisting a doctor. But Jane Stretch is no ordinary girl, and Mr Swift is no ordinary doctor.

Jane does her best to keep up with the doctor, her twisted bones throbbing, as they hurry past the markets, stage doors and side shows to appointments in certain boarding houses across town. The young actresses who live there have problems, and Mr Swift does what is required, calmly and discreetly. Grateful to her benefactor and his wife, Jane assists him and asks no questions - the desperate women not minding that it is a cripple girl who wipes their brows.

When this unlikely pair becomes involved with Johnny Treble, a rakish music hall star, and the police come knocking, it seems that Jane's spell of good fortune is unlikely to last...