London, October 1890. Crime-scene photographer Sarah Bain is overjoyed to marry her beloved Detective Sergeant Barrett - but the wedding takes a sinister turn when the body of a stabbing victim is discovered in the crypt of the church. Not every newlywed couple begins their marriage with a murder investigation, but Sarah and Barrett, along with their friends Lord Hugh Staunton and Mick O'Reilly, take the case.

The dead man is Charles Firth, whose profession is spirit photography, photographing the ghosts of the deceased. When Sarah develops the photographs he took in the church, she discovers one with a pale, blurred figure attacking the victim. The city's spiritualist community believes the church is haunted and the figure is a ghost. But Sarah is a skeptic, and she and her friends soon learn that the victim had plenty of enemies in the human world - including a scientist who studies supernatural phenomena, his psychic daughter, and an heiress on a campaign to debunk spiritualism and expose fraudulent mediums.

In the tunnels beneath a demolished jail, a ghost-hunting expedition ends with a new murder and new suspects. While Sarah searches for the truth about both crimes, she travels a dark, twisted path into her own family's sordid history. Her long-lost father is the prime suspect in a cold-case murder, and her reunion with him proves that even the most determined skeptic can be haunted by ghosts from the past.