M.M. Gaidar - The Highgate Ghost

The Highgate Ghost, the first in the series of novels and short stories about Cassandra Ayers, a woman detective who investigates supernatural crimes in London, 1900s. The series is called Cassandra's Demimonde.
A thirty-year-old Cassandra Ayers, a headstrong independent woman in a world ruled by men, is a skeptic detective intent on debunking supernatural phenomena. When she is confronted with grave desecrations at Highgate Cemetery said to be the work of a ghost, she finds a much more mundane explanation, and a murderous pair willing to kill to get away with crime.
Meanwhile, Cassandra is desperately trying to uncover the mystery of her own past. Why her mother committed suicide? Was her father involved in this? What terrible accident happened to Cassandra when she was thirteen?
When solving the case of Highgate Cemetery, Cassandra faces her own ghosts and she is finally to dig into her mother's death and find out what really killed her.