It includes a rogues' gallery of prostitutes, pimps, poisoners, pickpockets, murderers, and thieves. Female skills and knowledge were more and more demonised (witches, poisoners). All ideals are destructive, and all idealists are the poisoners of humanity. The fort had at one time served as a prison for Louis XIV's poisoners. The Doctor and his party return to the city, pleading clemency for the poisoners. This novel is a direct follow-up to "The Poisoners".