Kill-devil and water - Andrew Pepper

London: 1840. The economy is sliding into recession; gangs of unemployed workers roam the streets; the city is on the verge of anarchy and a murderer prowls the capital's poor neighbourhoods.
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.
Torn between his duties as a father and his instincts as an investigator, between grief for his wife and desire for one of his suspects, Pyke's investigation takes him from the London docks to the sugar plantations of Jamaica, from a fading colonial mansion to the back-street pornography shops of the East End and from the sewers beneath the city to the vaults of the Bank of England, in a struggle against ambitious and ruthless enemies, as well as demons of his own.