When clairvoyant Madame Katerina hosts a séance for three of Edinburgh's wealthiest families, she is stunned to hear that the following morning all of her guests have been found dead. She tells the police that a spirit killed the families for revenge, and although Detective "Nine Nails" McGray believes her, he must find a rational explanation that holds up in court. In mourning for his uncle and experiencing psychological trauma, Inspector Ian Frey is summoned to help, but the duo's fifth case (after Loch of the Dead) seems an impossible puzzle. Either something truly supernatural has occurred, or a fiendishly clever plot is covering a killer's tracks.