Number 4 Euston Square was a respectable boarding house, like many others in Victorian London. But beneath this ordinary veneer lurked a murderous darkness. On 8th May 1879, the corpse of former resident, Matilda Hacker, was uncovered in the coal cellar. The investigation that followed stripped bare the shadow-side of Victorian domesticity, throwing the lives of everyone within into an extraordinary maelstrom. Someone in Number 4 Euston Square must have killed Matilda Hacker. How could the murderer prove so elusive? Bestselling author Sinclair McKay delves into this intriguing story to shed light on a mystery that baffled Scotland Yard.