Once again Spence has taken hold of a Chinese historical event and transformed it into a fascinating tale that makes vivid the workings of China's security-obsessed imperial system. In 1728, the loyal governor-general of Shaanxi and Sichuan had thrust into his hands a seditious letter that called upon him, as the descendant of a man who had opposed the encroaching barbarians during the Song dynasty, to plot an overthrow of the "alien" Manchu dynasty. That innocent official had to convince the Manchu emperor that he had no treasonous thoughts. All manner of tricks and even torture were employed to test the loyalties of a circle of suspects, and the writings and the libraries of scholars were minutely examined for any hints of treason. To show his magnanimity, the emperor eventually pardoned the letter writer, but the succeeding emperor had him executed. Spence makes clear the fine line Chinese scholars had to walk between loyalty and treason as they fulfilled their duty to admonish the emperor for any moral lapses that might displease heaven -- and hence jeopardize the dynasty's legitimacy.