In Victorian London, after his life is saved by a young physician, a thief utilizes the knowledge he gains in prison and from the scientific lectures he attends as the physician's case study exhibit to create a new, highly successful, double life for himself.

In 1886 England, when fifteen-year-old Mariah begins working at the Prince Regent Hotel and discovers many previous workers have disappeared, he tries to solve the mystery, only to find that nothing is as it appears.

In late nineteenth-century London, fourteen-year-old Enola Holmes, much younger sister of detective Sherlock Holmes, turns to Florence Nightingale for help when her investigation into the disappearance of a Crimean War widow grows cold.