When the naked, mutilated body of a man is found in a Notting Hill graveyard and the police investigation led by Detective Chief Inspector Grant Foster and his colleague Detective Superintendent Heather Jenkins yields few results, a closer look at the corpse reveals that what looked at first glance like superficial knife wounds on the victim's chest is actually a string of carved letters and numbers, an index number referring to a file in city archives containing birth and death certificates and marriage licenses. Family historian Nigel Barnes is put on the case. As one after another victim is found in various locations all over London, each with a different mutilation but the same index number carved into their skin, Barnes and the police work frantically to figure out how the corresponding files are connected. With no clues to be found in the present, Barnes must now search the archives of the past to solve the mystery behind a string of 100-year-old murders. Only then will it be possible to stop the present series of gruesome killings, but will they be able to do so before the killer ensnares his next victim? Barnes, Foster, and Jenkins enter a race against time – and before the end of the investigation, one of them will get much too close for comfort.