1900. Seeking freedom from her authoritative father and the choking constraints of her aristocratic background, Cassandra Ayers runs away from home and settles in London where she intends to earn her living as a private detective. In Victorian society, overridden with superstitions and mysticism, she steadily gains a reputation for debunking paranormal activity.

In the first novel "The Highgate Ghost", Cassandra is hired to investigate the haunting of Highgate Cemetery where a few graves have been found desecrated and the groundsmen have been terrorized by something they are sure is a ghost.