The narrative begins on April 16, in an unspecified year of the 1940s. Dr. Bernard Rieux, leaving his office, unexpectedly discovers a dead rat in the stairwell of his building in Oran, a “thoroughly negative place” (1). Pushing the rat aside, Rieux makes his way downstairs. Once outside, the doctor realizes his mild discomfit and returns inside to inform the building’s concierge Michel, who assures him that the building is rat-free and chalks up Rieux’s odd finding to the work of young pranksters. Later that evening, Rieux encounters another rat—this one wobbly, squealing, and spurting blood from its mouth—in his building as he returns home.

Rather than prompting the doctor to consider potential signs of an impending epidemic, the sight of blood brings Rieux’s thoughts to his chronically ill wife, who will soon travel to a neighboring city to receive medical treatment in a sanatorium. In his wife’s absence, Rieux’s mother will come to Oran to keep house for him.

Making his habitual house calls, Rieux visits the home of an elderly bed-ridden Spaniard who suffers from asthma. As Rieux delivers his injection, the man notes that rats have been emerging around town. Over the following days, initial stages of panic grip the citizens of Oran as newspapers report that 8,000 dead rats have been collected throughout the city.