After the Civil War, a renewed interest in spiritualism caused hundreds of spiritualism mediums to set up shop in New York City by 1877. Dr. Gideon Mayhew works to discredit false mediums and to help their victims.

When Mayhew takes on what is routine case, he soon discovers that something more dark and dangerous is involved. The race to rescue an innocent girl from an unspeakable fate leads him into some of the most dangerous places a dangerous city has to offer.