Chandler and Miles attend the launch of Buchan's book on murders in Whitechapel, where they are baffled by cryptic remarks made by an eccentric old lady Louise Iver. At the same time, elderly vagrant Alexander Zukanov is lured to a house with strange markings on the wall where he is pressed to death, giving the name Dorothy Cade to his killer before he dies.
Miles and Chandler visit Zukanov's doss-house and learn that the other occupants were frightened of him and regarded him as a warlock. Buchan confirms that he was a member of the Bulgarian secret service and Stella Knight from MI6 names him as having been an interrogator of former British spy Crispin Wingfield. Wingfield is questioned but released though he tells the police that the manner of Zukanov's death was a punishment for witches in the sixteenth century.
Meanwhile, Dorothy Cade, living with her sister Cecilia, is also murdered, burnt at the stake like a medieval witch. The two cases are connected by the fact that the victims all died by burning at the stake, and it is believed that the crimes were committed by a woman known as the "Witchfinder General."
As the investigation progresses, Chandler and Miles uncover more evidence linking the victims to a group of witches who practiced black magic and were responsible for many deaths throughout history. They discover that the victims were all members of a sect called the "Order of the Black Hand," which was formed in the late 1700s to combat witchcraft and sorcery.
The Order of the Black Hand was led by a powerful woman named Martha Blackwood, who was responsible for the deaths of numerous innocent people. She was eventually captured and imprisoned, but her influence continued to spread through various underground groups.
As Chandler and Miles delve deeper into the case, they encounter a young woman named Eleanor, who claims to be a descendant of one of the victims. Eleanor reveals that she has been researching the Order of the Black Hand for years and believes that the true culprit is still alive today.
With the help of Cecilia, Dorothy's sister, they begin to piece together the puzzle of the past and uncover the secrets of the Order of the Black Hand. It is revealed that Martha Blackwood was actually a powerful sorceress who used her powers to control and manipulate those around her.
In the end, Chandler and Miles successfully bring Martha to justice, putting an end to the reign of terror that had plagued Whitechapel for centuries. The two detectives return home to their families, proud of what they have accomplished and grateful for the support and guidance they received along the way.
