Gadfium, the Chief Scientist of the ruling class, is engaged in a conspiracy with like-minded nobles who believe that the elite are not acting in the best interests of the population, and who question the real motive of the ongoing war with the rival clan of Engineers. She learns of a message apparently sent from the fast tower, the highest and previously inaccessible part of the castle, which stresses the danger of the Encroachment and tells of an attempt by the crypt to activate a long forgotten sub system which may prevent disaster. The message also warns that this will be opposed by those in power as it will threaten their interests. She and her fellow conspirators are considering how to respond when the security forces attempt to arrest them, although Gadfium manages to escape into the depths of the castle.