London, June 1759. When a charmless civil servant takes his own life, few are interested in his death. But Lizzie Hardwicke, who plies her trade in the brothels of London whilst also working as an undercover sleuth for the magistrate, can see no reason why a man who had everything to look forward to would wish to end his life.

Lizzie's search for answers takes her from the smoke-filled rooms of fashionable gambling houses, where politicians mix ambition with pleasure, to the violent streets of Soho, ready to erupt with riots in the sultry summer heat. All the while, she is navigating her complicated feelings for the magistrate's trusted assistant, Will Davenport, and a disturbing situation at home. Then a gambling house owner is brutally murdered, and Lizzie finds herself tangled in a chaos that she cannot control.

The darkest of secrets threatens to turn Davenport against her forever; its exposure will send her to the gallows.