Pentecost Alley — Anne Perry

The ritual murder of a prostitute named Ada McKinley in a bedroom on decrepit Pentecost Alley would ordinarily occasion no stir in Victoria's great metropolis. But, under the victim's body, the police find a Hellfire Club badge inscribed with the name Finlay Fitzjames--a name that instantly draws Superintendent Thomas Pitt into the case.

Finlay's father--immensely wealthy, powerful, and dangerous--refuses to consider the possibility that his son has been in Ada McKinley's bed. The implication is clear: Pitt is to arrest someone other than Finlay Fitzjames for Ada's demise. But Thomas Pitt is not a reran to be intimidated, and with the help of his quick-witted wife, Charlotte, he stubbornly pursues his investigation--one that twists and turns like London's own ancient streets....