Inspector William Monk: In search of justice, he will not stop until he has found the truth.

1864: When the body of a brutally mutilated body of a woman is found on Limehouse Pier, Monk's enquiries into her death unearth a suspicious connection between the victim and Dr Lambourn, a recently deceased scientist and staunch supporter for a new pharmaceutical bill aimed to regulate the sale of opium.

Investigating further, Monk learns that Lambourn's widow refuses to believe that her husband's death was suicide; she is convinced that he was murdered by government officials intent on keeping the lucrative trade of opium flowing.

With pressure mounting for the police to find the Limehouse killer, Monk is propelled headlong into an investigation that will delve the darkest depths of the opium trade and threatens to expose corruption in the very highest echelons of society...