Someone must have known what happened to Matilda Hacker. Standing four storeys tall in an elegant Bloomsbury terrace, No. 4, Euston Square was a well-kept, respectable boarding house. But beneath this genteel Victorian London veneer lay murderous intrigue. On 9 May 1879, the body of a former resident, Matilda Hacker, was discovered...
For someone in that house had killed her.
So how could the murderer prove so elusive?