George Chapman, also known as Severin Klosowski, was a London poisoner who was hanged in 1903. During his trial, a number of people began to suspect that he was, or had been, Jack the Ripper. These people included Frederick Abberline, who had been an important detective on the Ripper case back in 1888. Abberline became convinced that Chapman was his man. This novel takes Abberline's theory and runs with it.