London: 1840. Pyke, still grieving over the death of his wife and struggling to shoulder his responsibilities as a father, is in debtors' prison, having lost his home and reached the edge of bankruptcy. Fitzroy Tilling, now head of the new Metropolitan Police Force gives Pyke his freedom, but in return he must agree to investigate the brutal death of a young mulatto woman, recently arrived from Jamaica, and apparently working as a prostitute. Her body, found near the docks, has been viciously mutilated, but the police force are concentrating all their resources on the suspicious death of an influential aristocrat, and Pyke must therefore work alone. It is not long before another poor, young woman turns up dead, also mutilated and dumped by the river, and Pyke begins to suspect that he has stumbled on something more sinister, and more far-reaching than the murder of a couple of prostitutes.