London, 1885: Cora Burns has always struggled to control the violence inside of her. Does this temperament come from the mother she never knew, a convict who gave birth to her in jail? Cora finds work in the home of Thomas Jerwood, a gentleman-scientist obsessed with the study of hereditary criminality. Here Cora befriends a young girl, Violet, who seems to be the subject of a living experiment into upbringing and character. But are there two identical girls called Violet? And is Jerwood also secretly studying Cora? As the secrets of her past unravel, Cora must decide if her own scarred nature is an unalterable product of biology or if she has the strength to change.