Mo Hayder - The Devil of Nanking aka Tokyo

'There is an act, a very particular form of torture, which anthropologists and historians occasionally ruminate over. It is an act still reported from time to time from far-flung war zones around the world. What is unusual is that in spite of the oral evidence it has never been captured on film. But if film did exist, some people say, the most likely place it would come from, the place that was always whispered, the place that first comes to mind, is Nanking.'
Student Grey Hutchins comes to Tokyo seeking a rare piece of film showing the notorious Nanking Massacre in which, in one city, the Imperial Japanese Army butchered up to 300,000 civilians. Only one man can help her, a survivor of the massacre, and now a visiting professor at the prestigious University of Todai in Tokyo; a man who is rumoured to possess documentary evidence of Nanking.But first Grey must gain his trust. Desperate and alone, she accepts a job as a hostess in an upmarket nightspot catering for Japanese businessmen and wealthy gangsters. One gangster dominates – an old man in a wheelchair guarded by a terrifying entourage – who is said to rely on a powerful elixir for his continued wealth and well-being. It is an elixir that others want for themselves – at any price.
With its focus on the Tokyo underworld and China in the late 1930s, and a woman who has a lot to prove and even more to hide, this is a literary thriller of the highest order.