Modern-day homicide detective Mallory Mitchell has grown accustomed to life in Victorian Scotland after travelling 150 years into the past into the body of a housemaid. She’s built a new life for herself. Even though she works as an assistant to forensic-science pioneer Dr. Duncan Gray and Detective Hugh McCreadie, she considers them true friends. And with Gray in particular, perhaps, someday, something more. 

Late one night, Gray and Mallory are summoned urgently to the home of Lady Adler, a patron of Gray’s undertaking business, and they assume there’s been a death in the household. But instead, they arrive in the midst of a seance with a ghost demanding Gray’s presence. The ghost is Lady Adler’s former maid, who had gone missing but now requests that Gray investigate her murder. Although Gray and Mallory are skeptical, they agree to look into the matter, whether she’s dead or alive. But unsure if there’s been a murder or not, unable to call out the medium as a fraud, and concerned for the fate of the young maid, Gray and Mallory are once again drawn into a mystery much more puzzling–and more dangerous–than it first seems