Number 4 Euston Square was a respectable boarding house, well-kept and hospitable, like many others in Victorian London. But beneath this very ordinary veneer, there was a murderous darkness at the heart of this particular house. On 8th May 1879, the corpse of former resident, Matilda Hacker, was uncovered by chance in the coal cellar. The investigation that followed this macabre discovery stripped bare the shadow-side of Victorian domesticity, throwing the lives of everyone within into an extraordinary and destructive maelstrom. For someone in Number 4 Euston Square must have had full knowledge of what had happened to Matilda Hacker. Someone in that house had killed her. How could the murderer prove so amazingly elusive? Bestselling author, Sinclair McKay delves into this intriguing story and sheds light on a mystery that eluded the detectives of Scotland Yard.