Although the novel is fictional, it parallels the history of Shanghai during the 1920s, showing the negative impact of colonialism on the city. It depicts European powers exploiting the native Chinese residents to gain power and resources. At the start of the novel, foreign nations have carved up the city in sections, leaving few “Chinese-owned zones” (57). The Scarlet Gang tolerate the foreigners’ presence because they stimulate the economy, and the gang stands to profit. However, Juliette worries that they are making a mistake in working with the foreigners: “Juliette feared the tables would turn suddenly one day, leaving the Scarlet Gang to realize they had found themselves standing on the outside” (58). Although the foreigners boost the city’s economy, this comes at a cost. Chinese residents are treated as second-class citizens, excluded from some establishments. While the madness spreads, the Europeans flaunt their wealth, ignoring the suffering of the afflicted. As a result, both the Nationalists and the Communists organize against the foreign interests.

Furthermore, Paul Dexter’s plot to profit by infecting the city with a madness then providing its cure is a metaphor for the European’s callous treatment of the Chinese in Shanghai.