The Plague concerns an outbreak of bubonic plague in the French-Algerian port city of Oran, sometime in the 1940s. The first-person narrator is unnamed but mostly follows Dr. Bernard Rieux. Rieux notices the sudden appearance of dying rats around town, and soon thousands of rats are coming out into the open to die. The public grows panicked, and the government finally arranges a daily cremation of rat bodies. Soon after the rat epidemic disappears, M. Michel, the concierge for Dr. Rieux’s office building, comes down with a strange fever and dies. More cases appear, and Dr. Rieux and his colleague Dr. Castel believe the disease is bubonic plague. They urge the government to take action, but the authorities drag their feet until the death toll rises so high that the plague is impossible to deny. Finally they close the gates and quarantine Oran.
The townspeople react to their sudden isolation with feelings of exile and longing for absent loved ones, with each individual assuming that their suffering is unique. Father Paneloux, a Jesuit priest, delivers a sermon declaring that the plague is a divine punishment for Oran’s sins. Raymond Rambert, a foreign journalist, tries to escape Oran and rejoin his wife in Paris, but he is held up by the bureaucracy and the unreliability of the criminal underground. He is aided in his attempts by Cottard, a man who committed an unknown crime in the past and has since then lived in constant paranoia. Cottard is the only citizen to welcome the plague, as it reduces the rest of the public to his level of fear and loneliness, and he builds up a small fortune smuggling. Meanwhile Rieux struggles ceaselessly against the plague and is joined by Jean Tarrou, another visitor to Oran, and Joseph Grand, an older municipal clerk who longs for his ex-wife and struggles daily over the first sentence of a book he is trying to write.
Tarrou organizes an anti-plague sanitation league, and many volunteers join to help. Rambert finalizes his escape plan, but when he learns that Dr. Rieux is also separated from his wife (who is ill in a sanatorium) he decides to stay and fight the plague. After several months the public loses the selfishness in their suffering and recognizes the plague as a collective disaster. Everyone grows weary and depressed, and the death toll is so high that the authorities have to cremate the bodies. The young son of M. Othon, the strict local magistrate, comes down with the plague and Rieux and his companions – among them Father Paneloux – watch him suffer and die. Paneloux is shaken by the child’s death and he delivers a second sermon, this time declaring that the horrors of plague leave only the choice to believe everything (about Christianity) or deny everything. Paneloux falls ill and dies soon afterwards, though he does not have the symptoms of the plague.
Tarrou explains to Rieux how he has spent his life opposing the death penalty and “fighting the plague” in its many forms. The two men take a brief break to go swimming and then they go back to work. Grand falls ill with the plague, but then he makes a miraculous recovery. Other patients recover as well, and soon the epidemic is on the retreat, but then Tarrou falls ill. After a long struggle against the disease he dies. The townspeople slowly regain their hope and begin to celebrate. Only Cottard is upset by the end of the plague, and on the day the town’s gates reopen, he goes mad and starts randomly firing a gun into the street until he is arrested. Grand writes a letter to his ex-wife and resumes work on his book. Rambert’s wife joins him in Oran, but Dr. Rieux learns that his wife has died at the sanatorium. The townspeople quickly return to their normal lives, trying to pretend nothing has changed. Dr. Rieux reveals himself as the narrator of the chronicle, which he wrote as a testament to the victims of the plague and the struggles of the workers. He knows the victory over the plague is only temporary, as the bacillus microbe can lie dormant for years.