The madness that spreads across the city through insects and the monster that lurks in the river represent the dual nature of Shanghai and of the novel. The madness’s origin symbolizes the combination of outside capitalist interests and the violence endemic to the city. A foreigner, Paul Dexter, imports the insects that cause the madness into the city, but when he tries to infect Qi Ren with it, it morphs, causing Qi Ren to become a monster that spreads the madness across the city. Dexter profits from the mass suicides the madness causes by offering a vaccine to prevent the disease. Thus, the madness is both a symbol of the profiteering of colonists and a metaphor for the contagious gang violence already occurring in the city. In the first scene, the madness ironically intervenes between the two warring gangs, causing them each to die by suicide rather than kill one another. Its infectiousness resembles the contagious nature of the blood feud between the gangs, in which one act of violence leads to an endless cycle of retaliation.