The story opens in Philadelphia in 1793. The city, one of the centers of commerce and culture of the early United States, is gripped in the throes of a yellow fever epidemic. Those people with the means have fled the infected city, while the poor have been forced to remain behind, most likely to die. The city has essentially closed down.

The story's primary narrator is an African-American man called Allen. Although Allen has a wife and daughter, he has chosen to stay in the city, where he works for Dr. Rush, a practitioner determined to treat the fever's victims and understand the cause of the disease. Allen, once the founder of an African-American church, now spends his days caring for the sick and dying and burying the dead.

According to white Philadelphians, the disease has been brought to the city by slaves from Santo Domingo (present-day...