An Enemy of the People (original Norwegian title: En folkefiende) is an 1882 play by Norwegian playwright Henrik Ibsen that explores the conflict between personal integrity and societal norms. The play centers on Dr. Thomas Stockmann, who discovers a serious contamination issue in his town's new spas, endangering public health. His courageous decision to expose this truth brings severe backlash from local leaders, including his brother Peter Stockmann, who is a powerful political figure in the town.

Set against the backdrop of a community grappling with economic and environmental concerns, the play highlights the often harsh consequences faced by those who challenge established systems. Ibsen’s depiction of this struggle emphasizes the tension between truth and expediency. The character of Peter Stockmann is based on Ibsen’s own uncle, Christian Cornelius Paus, whose political influence and authoritative role in Ibsen's hometown of Skien parallel those of Peter in the play. Ibsen himself was uncertain about the play's classification, noting in a letter to his publisher that it contained both comedic and serious elements, reflecting his complex view of the protagonist's moral stance. This exploration of moral and societal conflict follows Ibsen’s earlier work, Ghosts, which faced similar criticism for its bold critique of societal norms.

Dr. Thomas Stockmann is the medical officer of a recently opened spa in a small town. The play begins with a dinner party hosted by Dr. Stockmann and his wife, Katrine. The dinner guests include Dr. Stockmann's brother Peter (the mayor) and Hovstad (the editor of the newspaper). Peter asks Stockmann about a rumor that Hovstad is about to print an article the doctor wrote regarding the spa baths. Dr. Stockmann is evasive about the nature of this article, and Peter leaves. Petra, Dr. Stockmann's daughter, brings in a letter containing lab test results confirming Dr. Stockmann's suspicions that the spa water is contaminated with bacteria, and Hovstad agrees to print Dr. Stockmann's article, although revealing the truth may force the baths to shut down, with negative repercussions for the town's economy. Dr. Stockmann has mixed reactions to these events but ultimately rejoices about preventing the harm that the contaminated water would have caused.

The next morning Morten Kiil, Dr. Stockmann's father-in-law, stops by to congratulate him on what Kiil believes is an elaborate prank, since Kiil thinks the notion that the baths are tainted is too ridiculous to be believed, especially not by the mayor. Hovstad and the printer Aslaksen visit to reinforce their commitment to the doctor and extend their gratitude; the newspaper wants to confront the government of the town and expose its corruption, and this opportunity is a good start.

Peter arrives and tells Dr. Stockmann that if he selfishly proceeds to publish this article, he will be partially culpable for the town's ruin. Peter urges Dr. Stockmann to think of the bigger picture, retract the article, and solve the problem in a quieter way. Dr. Stockmann refuses; Peter warns of terrible consequences for him and his family.

In the newspaper office, Hovstad and the sub-editor, Billing, discuss the pros and cons of running Dr. Stockmann's article. Dr. Stockmann arrives and tells them to print the article, but they begin questioning how valuable it is to expose the government in this way, concluding that printing this article will do more harm than good, because of its likely effect on the town's economy. Peter Stockmann appears with a statement of his own, intended to reassure the public about the safety of the spa baths, and the newspaper agrees to print it. Desperate, Dr. Stockmann decides that he does not need the paper to print anything and that he can fight this battle on his own. He decides to call a town meeting and spread the information that way. Although Katrine Stockmann realizes that her husband is risking his reputation, she stands by him.

At a town meeting in Captain Horster's house, Dr. Stockmann is about to read his water report to the townspeople. Billing, the family, the mayor, Aslaksen, and Hovstad are there. Aslaksen, a respected citizen, is elected Chairman of the meeting. Permission for Dr. Stockmann's being allowed to speak is about to be voted on, when Dr. Stockmann says he has a different subject. He then winds up into a passionate oration about social evolution. He says that new, truthful ideas are always condemned, due to the "colossal stupidity of the authorities" and the small-mindedness of "the compact liberal majority" of the people, who may as well "be exterminated." The audience feels insulted by these accusations and anger rises. By the end of the meeting the audience has rebelled, repeatedly shouting, "He is an enemy of the people!" Dr. Stockmann tells his father-in-law, Kiil, that it is his tannery that is leaking most of the poisons into the baths. As the crowd is leaving, voices are heard threatening to break Stockmann's windows.

By the next morning, Dr. Stockmann's house, especially his study, has been badly damaged, for the town has turned against him and his family. The landlord is evicting them from their house; Petra has been fired from her job as a schoolteacher for having progressive opinions; Peter comes to the house with a letter from the board of directors of the baths that terminates his contract along with a resolution from the homeowners' association stating that no one should hire Dr. Stockmann in this town again.