Can Monk uncover the truth behind a deadly opium conspiracy? 1864 and on the bank of the Thames, Monk is appalled at the shocking mutilation visited upon the body of a woman found on Limehouse Pier. But when enquiries into the brutal killing unearth a connection between the victim and Dr Lambourn, a brilliant, recently deceased scientist and staunch supporter for a new pharmaceutical bill aimed to regulate the sale of opium, it becomes clear that not all is as it seems. Lambourn's widow refuses to believe the official verdict that her husband's death was suicide; she is convinced that he was murdered after the research he was conducting was discredited by government officials intent on keeping the lucrative trade of opium flowing. With pressure mounting for the river police to find the Limehouse killer, Monk is propelled headlong into an investigation that will delve into the darkest depths of the opium trade and threaten to expose corruption in the very highest echelons of society ...