The Great War had been in progress for two years, and the nation was still reeling from the losses at the Battle of the Somme.  It is September 1916, and a Zeppelin aiming for Victoria railway station discharges its deadly cargo of bombs on central London.  But instead of hitting the station, the bombs destroy a house in nearby Washbourne Street, killing all the occupants.

 

In the basement of the house, police make a grisly discovery that presents Divisional Detective Inspector Ernest Hardcastle of the Metropolitan Police with a convoluted murder enquiry.  Then, a second murder, apparently connected with the first, complicates the investigation. 

 

Aided by Detective Sergeant Charles Marriott, the intrepid Hardcastle questions a titled entrepreneur and his wife, an earl’s daughter and her army officer husband, countless prostitutes, a pair of butlers, and attends a court martial before the killer is eventually brought to trial.