On May 9, 1879, an elegant Bloomsbury boarding house became the center of a murder investigation. In the coal cellar, the body of a former resident, Matilda Hacker, was discovered by chance. The ensuing investigation—led by Inspector Charles Hagen, rising star of the recently formed Criminal Investigation Department—exposed the dark side of Victorian domesticity. A surprising suspect was arrested and tried, but here the author of The Secret Life of Bletchley Park digs deeper in an attempt to solve this puzzling case.